- Email: [email protected]
Luteal cysts and unexplained infertility: biochemical and ultrasonic evaluation*
Vol. 54, No.1, July 1990
FERTILITY AND STERILITY Copyright ~ 1990 The American Fertility Society
Printed on acid-free paper in U.S.A.
Luteal cysts and unexplained infertility: biochemical and ultrasonic evaluation*
Mark P. R. Hamilton, M.D.t:j:§ Richard Fleming, Ph.D.t John R. T. Coutts, Ph.D.t
Malcolm C. Macnaughton, M.D.t Charles R. Whitfield, M.D.§
University of Glasgow, Glasgow, Scotland
A prospective, controlled study of ovarian function using ovarian ultrasound and daily plasma hormone estimations (estradiol, progesterone [P], follicle-stimulating hormone [FSH], luteinizing hormone [LH]) was carried out on 175 spontaneously cycling patients with unexplained infertility. Forty-one (23.4%) demonstrated luteal phase cyst formation. In 21 cycles the dominant follicle reduced in size after the LH peak (cystic corpus luteum cycles), and in 20 no shrinkage was seen (luteinized unruptured follicles). Progesterone concentrations in the early luteal phase were significantly reduced in the luteinized unruptured follicle cycles. Elevation in plasma FSH was seen in the early follicular and luteal phases of both cyst forming groups and may be due to disturbances in ovarian metabolism. Follicular rupture is important for efficient P release by the corpus luteum. Fertil Steril 54:32, 1990
The assumptions that ovulation is an inevitable consequence of a luteinizing hormone (LH) surge and that a "normal" plasma progesterone (P) Concentration is always associated with ovulation have been questioned for some time. That infertility might be a consequence of repeated oocyte entrapment within an unruptured follicle, in the presence of biochemical and endometrial evidence of "normal ovulation," has also been a matter of considerable speculation. 1-3 The concept of a luteinized unruptured follicle has been explored extensively using laparoscopy4 and analyses of peritoneal fluid ovarian steroids. 5 In addition, ovarian ultrasound (US) provides a direct means of evaluation of ovarian function. 6,7 In
the normal cycle, the dominant follicle shrinks and becomes infilled after the LH peak, but, in a proportion of cases, its cystic nature can be seen to persist during the luteal phase. 7,8 The use of ovarian US to define the luteinized unruptured follicle syndrome, both in stimulated9-11 and unstimulated cycles,12-15 has been used extensively. Understanding the pathogenesis of these phenomena has been hampered through lack of numbers,9,12 variation in the US criteria for the diagnosis of luteinized unruptured follicle syndrome, failure to relate the observations to biochemical indices of pituitary and ovarian function,8,10,13-15 and lack of uniformity of the patients under study. 11,16
Received November 13, 1989; revised and accepted March 13, 1990. * Supported by grant G8200415 SB from the Medical Research Council, London, United Kingdom. t Department of Obstetrics and Gynaecology. :j: Reprint requests: Mark P.R. Hamilton, M.D., Department of Obstetrics and Gynaecology, Royal Infirmary, Alexandra Parade' Glasgow G312ER, Scotland. § Department of Midwifery.
The present study was designed to effect longitudinal assessments of ovarian function prospectively in a large population of women with unexplained infertility. Repeated US evaluations offollicular growth profiles were compared with suitable controls, and the incidence and natural history of US observed luteal phase cysts were determined. The relationships of these phenomena to pituitary and ovarian hormone profiles were analyzed to
32
Hamilton et al.
Luteal cyst formation
Fertility and Sterility
study the possible pathogenic mechanisms involved in the US abnormalities seen. MATERIALS AND METHODS
ceptive use over the previous 6 months; and no sexual activity during the cycle of investigation. The age of the controls ranged from 18 to 36 years (median 26 years).
Patients and Blood Samples
Analyses and Statistics
The study group comprised 175 patients with >3 years unexplained infertility-normal menstrual rhythm (cycle length 24 to 41 days), normallaparoscopy within the previous 2 years, male partner normal, normal postcoital test, and no sexual problems. All underwent a fixed protocol of investigation. A blood sample (10 mL) was taken from every patient at the same time of day throughout the entire menstrual cycle and each plasma separated and stored at -20°C for retrospective analyses. Sensitive, specific, and precise radioimmunoassays for 17/3-estradiol (E 2 ), P, LH, and follicle-stimulating hormone (FSH) were carried out on all samplesP Samples from a complete cycle were analyzed in a single batch to eliminate the effects of interassay variations when evaluating a single profile.
The cycles were organized around the day of the LH peak (day 0). Days before this (follicular phase) were denoted negative, and days after this (luteal phase) were denoted positive. A P index was calculated for the area under the curve of P concentrations in the early luteal phase of each cycle. This index was the sum of all P values from days +2 to +6 in the study cycle, expressed as a percentage of the mean of the control population P concentrations over the same period. No assumption was made regarding the distribution of the data in respect to the study and control cycles, and, except where indicated, a nonparametric method of statistical analysis (Wilcoxon rank sum test) was employed to determine differences between groups.
Ultrasound Scans
Luteal cyst formation was diagnosed when a cystic structure was observed, between days +5 and +8, in the ovary that had contained the dominant follicle. The diameters of the cysts were calculated on the basis of the mean of all diameters measured between days +5 and +8.
Scans were performed by a single operator (M.P.R.H.) using a B-mode static scanner (Nuclear Enterprises 4201, Fischer, Edinburgh, Scotland) with a 3.5 MHz probe, calibrated to 1,540 m/s. The full bladder technique permitted visualization of the developing Graafian follicle, which was measured in three dimensions, follicular diameter being expressed as a mean of these three measurements. Scans were carried out from the 8th day ofthe cycle onward. Once identified, the developing follicle was monitored through daily scans until the characteristic infilling as it became a corpus luteum (CL) was observed. All patients underwent at least three US examinations in the luteal phase, and if a cystic structure persisted in the ovary, US monitoring continued at 48 hourly intervals until menstruation ensued. Controls
Forty-three women of reproductive age volunteered to undergo investigation using a similar protocol of blood samples and US scans. Criteria for inclusion were: normal menstrual rhythm (24 to 41 days) over the preceding 6 months; no past history of gynecological disease; no history of oral contraVol. 54, No.1, July 1990
Definition of Luteal Cyst
RESULTS
Forty-one (23.4%) of the 175 patients under study showed luteal cyst formation. Median age of these patients was 29 years (range 22 to 39 years), similar to the rest of the unexplained infertile population. Median follicular phase duration (1st day of menses up to and including day 0) was 14 days (range 8 to 27 days), and luteal phase length (day +1 to day before onset of next period inclusive) ranged from 11 to 18 days (median 15 days). These cycle characteristics were similar to those of the control population. None of the 43 control cycles showed luteal cyst formation (x 2 = 12.41, P < 0.0001). Frequent scanning during the periovulatory period permitted discrimination between those cycles where the dominant follicle was seen to reduce in size immediately after the LH peak (21 cycles [51.2% of the cyst group]), and those where Hamilton et at.
Luteal cyst formation
33
Table 1 Luteal Cyst Formation in Patients With Unexplained Infertility (n = 175)
Group
Percentage of cysts
No.
Cyst formers Large cysts (>20 mm) Small cysts «20 mm) Shrinkers Nonshrinkers
41 30 11 21 20
240 200
Percentage of series 23.4 17.1 6.3 12.0 11.4
100.0 73.2 26.8 51.2 48.8
E2
160 120
o the dominant follicle showed no evidence of shrinkage after day 0 (20 cycles [48.8%]) (Table 1). Figures 1, 2, 3, 4, and 5 detail the follicular diameter, E 2 , P, FSH, and LH data relating to these subgroups of cyst formers, i.e., shrinkers and nonshrinkers. The median values in both groups are plotted against the 95% confidence limits of the control data, represented by the shaded area on each graph. Statistical significance, where found, in comparison between the groups and also with the control data, is presented. Follicular Diameters
There was no difference (Fig. 1) between the two study groups or the controls in follicular diameter profiles up to and including day O. Divergence from normal occurred from day +1 onward. Median cyst size was significantly greater in the nonshrinkage (33.0 mm) compared with the shrinkage cycles (18.5 mm, P < 0.001). An arbitrary distinction was made between large (follicular diameter> 20 mm) and small (follicular
NO SIGNIFICANT DIFFERENCES BETWEEN THE GROUPS AND IN COMPARISON WITH CONTROLS.
- 10
-5
0
5
10
15
Day relative to LH peak Figure 2 Median plasma E2 concentrations (pg/mL) (days -10 to +14) in luteal cyst cycles (shrinkers n = 21, nonshrinkers n = 20). Shaded area represents 95% confidence limits of the control population (n = 43). No significant difference (Wilcoxon rank sum test) compared with controls or between groups.
diameter < 20 mm) luteal phase cysts based on the mean diameter ofthe dominant follicle in the control cycles on day 0, i.e., 20.2 mm. Large luteal cysts were found in 30 ofthe 41 cycles (73.2%), whereas small cysts were seen in 11 cycles (26.8%) (Table 1). Ten (33.3%) of the large luteal cyst cycles exhibited shrinkage of the dominant follicle after the LH peak. 17tJ-Estradiol
The E2 profiles (Fig. 2) were virtually identical in both groups of cyst formers and no different from the controls. IIEDIAN P INDICES
25
Conlroft 1011.0 Shr/nkmlM (N.s.) Non-.hrlnk". 53.5 (p <0.0(11)
40 20 35
15
30
FD 25
P
20
10
ng/ml 5
mm.
15
O~--------r--r------------~-'r-~ i iv
- 8
- 6
i
•.
-4
-2
i i i
0
2
4
iv
i
i
I
6
8
Day relative to LH peak Figure 1 Median follicular diameters (mm) (days -6 to +8) in luteal cyst cycles (shrinkers n = 21, nonshrinkers n = 20). Shaded area represents 95% confidence limits of the control population (n = 43). Up to day 0 no significant differences (Wilcoxon rank sum test) compared with controls. Significance between the groups: i, P < 0.05; ii, P < 0.02; iii, P < 0.01; iv, P < 0.001.
34
Hamilton et al.
Luteal cyst formation
,
o
z
Y
2
4
z
w
6
8
w
10
12
14
Day relative to LH peak Figure 3 Median plasma P concentrations (ng/mL) (days 0 to + 14) in luteal cyst cycles (shrinkers n = 21, nonshrinkers n = 20). Shaded area represents 95% confidence limits ofthe control population (n = 43). Significance compared with controls (Wilcoxon rank sum test): shrinkers: a, P < 0.05; b, P < 0.02; d, P < 0.001; nonshrinkers: w, P < 0.05; x, P < 0.02; y, P < 0.01; Z, P < 0.001. Significance between groups: i, P < 0.05; ii, P < 0.02; iii, P < 0.01.
Fertility and Sterility
14
DISCUSSION
12 10
FSH
lUll
-,'
Or-~~b-C~-------------------------- I W
-10
-5
0
W I
W •
5
x
10
15
Day relative to LH peak Figure 4 Median plasma FSH concentrations (lUlL) (days -10 to +14) in luteal cyst cycles (shrinkers n = 21, nonshrinkers n = 20). Shaded area represents 95% confidence limits of the control population (n = 43). Significance compared with controls (Wilcoxon rank sum test): shrinkers: a, P < 0.05; b, P < 0.02; c, P < 0.01; nonshrinkers: w, P < 0.05; x, P < 0.02; y, P < 0.01. Significance between groups: i, P < 0.05.
Progesterone
Progesterone concentrations (Fig. 3) in the cycles where no shrinkage of the dominant follicle was seen after the LH peak were profoundly reduced (median P index 53.5) compared with the control cycles (P index 100.0, P < 0.001) and to the cycles where shrinkage of the follicle was observed (median P index 84.0, P < 0.001). Although P concentrations were reduced in the cycles showing shrinkage, the difference was not significant compared with the controls. Follicle-Stimulating Hormone
In those cycles where shrinkage of the follicle was observed (Fig. 4), FSH concentrations in the early follicular phase (days -9 to -6) were significantly higher compared with the control data. In comparison with the nonshrinkage cycles, plasma FSH also tended to be higher, though this achieved statistical significance only on day -7. Midcycle concentrations were similar to the controls in both groups. In the luteal phase, there were minor differences in both groups compared with the controls. This was more pronounced in the cycles where no shrinkage was s~en (lower P concentrations), with FSH concentrations significantly elevated in the midluteal phase (days +6 to + 10). Luteinizing Hormone
Figure 5 shows the profiles of LH in both study groups and in the controls were similar throughout the cycle. Vol. 54, No.1, July 1990
This study represents a prospective, controlled analysis of ovarian function in a large population of spontaneously cycling women with unexplained infertility. Luteal cyst formation was the most common US abnormality detected, seen in almost a quarter ofthe patients under study. In half ofthese cycles, no evidence of follicular reduction in size preceded luteal cyst formation. Associations of these US profiles with diminished plasma concentrations of P in the early luteal phase and elevated concentrations of FSH in the follicular and luteal phase have been shown. This is the first substantial evidence combining biochemical and US data on such abnormalities in a uniform population. The differing US profiles seen after the LH peak suggest that two distinct pathophysiological mechanisms may be involved in luteal cyst formation. Those cycles where no shrinkage of the dominant follicle occurred after the LH peak, and where P concentrations were profoundly reduced, may represent the luteinized unruptured follicle syndrome. The other group, where some shrinkage (rupture?) of the dominant follicle was observed, were associated with marginally reduced plasma P concentrations and could be described as cycles with cystic CL formation. The US data suggest that ovulation could have occurred in the cystic CL cycles, but since similar US profiles were not seen in the control cycles, both phenomena may indicate an infertile cycle among this subfertile population. These events could not be predicted on the basis of follicular maturation as assessed by either circulating E2 75 non - shrlnker.
60
/'
45
LH
30
lUll 15
__...
,',
a.~
, , '.
o
~
NO SIGNIFICANT DIFFERENCES BETWEEN THE GROUPS AND IN COMPARISON WITH CONTROLS
-10
- 5
0
5
10
15
Day relative to LH peak Figure 5 Median plasma LH concentrations (lUlL) (days -10 to +14) in luteal cyst cycles (shrinkers n = 21, nonshrinkers n = 20). Shaded area represents 95% confidence limits of the control population (n = 43). No significant difference (Wilcoxon rank sum test) compared with controls or between groups. Hamilton et al.
Luteal cyst formation
35
concentrations or follicular phase follicular diameter patterns, and the size of the luteal cyst did not discriminate between the two groups. Only 2 of the 20 luteinized unruptured follicle cycles were associated with a normal P index as compared with 17 of the 21 cystic CL cycles (x 2 = 20.7, P < 0.0001). These data lend support to the concept that follicular rupture is a necessity for efficient P production in the luteal phase. A previous study16 on a small, heterogeneous group of patients, a minority with unexplained infertility, described similar patterns of luteal cyst formation. Cycles demonstrating US evidence of shrinkage were described as the luteinized unruptured follicle syndrome and were associated with normal luteal phase P concentrations. Expansion of a luteal cyst after US evidence of shrinkage (seen in 10 of the 21 cystic CL cycles described in the present study) was not observed in their series. Their data contrast with our own, which suggest that luteinized unruptured follicle cycles, often associated with diminished P concentrations in the luteal phase, are characterized by follicular expansion without prior reduction in size. The role of LD L in steroid synthesis in the luteal phase 18 is well established. In the normal CL, granulosa lutein cells enjoy intimate contact with capillary blood from which they take up steroid precursors for P synthesis. Disruption of the basement membrane barrier between blood and the granulosa lutein cells is probably necessary for the initiation and maintenance of CL function. The lag in P production observed in the nonshrinkage cycles could be explained by impairment of angiogenesis after the LH surge, leading to diminished availability of steroid precursors and release of P into the circulation. In cycles with normal P indices, most of which occurred in the group demonstrating evidence of follicular shrinkage, availability of precursors in the early luteal phase was probably unaffected, despite luteal cyst formation. This provides evidence that limited US data of periovulatory follicular dynamics cannot discriminate absolutely between normal and abnormal potential for steroid production, or ovulation. There is no doubt that the human luteotrophic complex requires LH, but it is probable that other factors influence steroid biosynthesis as well. In both subgroups, FSH concentrations were found to be slightly higher than the controls in the midluteal phase. It is possible that FSH is involved in the luteotrophic influence at this point in the cycle, acting on its receptor in the granulosa cell mem36
Hamilton et al.
Luteal cyst formation
brane. 19 The finding of high luteal phase FSH concentrations in many of the luteinized unruptured follicle cycles could represent an attempt at compensation for defective luteal function, but the mediator between the ovary and the pituitary in this situation is unclear since E2 concentrations were no different from normal cycle patterns and were similar in the two groups. Circulating inhibin concentrations have been found to rise in the luteal phase ofthe normal cycle,20 and it may be hypothesized that luteal cyst formation is associated with reduced concentrations of inhibin resulting in elevated concentrations of FSH. Inhibin concentrations in cycles with cyst formation have not been evaluated. Previous publications have implicated reduced early follicular phase (perimenstrual) FSH concentrations in the pathogenesis of luteal phase deficiency.1,3,21,22 The data presented here show no relationship between these phenomena and suggest that enhancement of gonadotropin activity in the early part of the follicular phase using antiestrogens, or by administration of exogenous gonadotropins, would be of little therapeutic value. It is possible that the two groups presented here may not be as distinct as their US and biochemical patterns suggest. The process of ovum release may not always be consequent on US observed follicular shrinkage,23 and ovum entrapment may have occurred in some ofthe cycles where shrinkage of the dominant follicle was observed. Conversely, in some of the non shrinking cyst formers, it is possible that a diminution in the size of the follicle might have been missed in the periods between US observations. This type of error was kept to a minimum by the endeavor to scan patients every day over the periovulatory period. However, it is possible, since the processes of follicular rupture as observed ultrasonically take place over a relatively short period of time, 24 that some overlap of the two groups of cycles occurred. The difference in P profiles of the two groups is circumstantial evidence that the discrimination is accurate and real. In conclusion, it has been shown that although there is a close relationship between US and hormonal assessment of CL function, definition of luteal phase abnormalities requires consideration of biochemical and US indices together, rather than independently. Cycles with luteal cyst formation do not represent a homogeneous population, and the ultimate size of the cyst is not a sensitive indicator of the nature of the structure or its relationship with CL hormone output. Shrinkage of the Fertility and Sterility
dominant follicle before cyst formation appears to be a major determining factor of the steroidogenic potential of the luteinized follicle but may not be the only one. The effect on fecundity of luteal phase deficiency can possibly be explained by three mechanisms: failure of oocyte release, abnormal follicular metabolism, and potential disturbances in endometrial receptivity mediated through diminished circulating P concentrations. Continued infertility is most likely due to the frequency with which such disturbances recur. Acknowledgments. The assistance of the laboratory staff of the Department of Obstetrics and Gynaecology, Royal Infirmary, Glasgow, and ofthe staff ofthe Department of Ultrasonic Technology, Queen Mother's Hospital, Glasgow, is gratefully acknowledged.
REFERENCES 1. Sherman BM, Korenman SG: Measurement of plasma LH, FSH, estradiol and progesterone in disorders of the human menstrual cycle: the inadequate luteal phase. J Clin Endocrinol Metab 39:145,1974 2. Jewelewicz R: Management of infertility resulting from anovulation. Am J Obstet Gynecol122:909, 1975 3. Jones GS, Maffezoli RD, Strott GA, Ross GT, Kaplan G: Pathophysiology of reproductive failure after clomiphene induced ovulation. Am J Obstet Gynecol108:84 7, 1970 4. Koninckx PR, Heyns WJ, Corvelyn PA, Brosens IA: Delayed onset of luteinization as a cause of infertility. Fertil Steril 29:266, 1978 5. Devroey P, Temmerman M, Verhoeven N, Naaktgeboren N, Heip J, Amy JJ, Van Steirteghem AC: Recurrence ofthe luteinized unruptured follicle. Br J Obstet Gynaeco190:381, 1983 6. Hackeloer BJ, Fleming R, Robinson HP, Adam AH, Coutts JRT: Correlation of ultrasonic and endocrinologic assessment of human follicular development. Am J Obstet Gynecol 135:122, 1979 7. Queenan JT, O'Brien GD, Bains LM, Simpson J, Collins WP, Campbell S: Ultrasound scanning of ovaries to detect ovulation in women. Fertil Steril34:99, 1980 8. Nitschke-Dabelstein S, Hackeloer BJ, Sturm G: Ovulation and corpus luteum formation observed by ultrasonography. Ultrasound Med BioI 7:33, 1981 9. Coulam CB, Hill LM, Breckle R: Ultrasonic evidence for luteinization of unruptured preovulatory follicles. Fertil Steril 37:524, 1982
Vol. 54, No.1, July 1990
10. Gibbons WE, Buttram VC, Jr, Rossavik IK: The observed incidence of luteinized unruptured follicles in a population of infertile women undergoing ovulation monitoring by ultrasound. (Abstr. 44) Fertil Steril41:19S, 1984 11. Hamilton CJCM, Wetzels LCG, Evers JLH, Hoogland HJ, Muijtjens A, de Haan J: Follicle growth curves and hormonal patterns in patients with the luteinized unruptured follicle syndrome. Fertil Steril43:541, 1985 12. Coutts JRT, Adam AH, Fleming R: The deficient luteal phase may represent an anovulatory cycle. Clin Endocrinol (Oxf) 17:384,1982 13. Kerin JF, Kirby C, Morris D, McEvoy M, Ward B, Cox LW: Incidence of the luteinized unruptured follicle phenomenon in cycling women. Fertil Steril 40:620, 1983 14. Liukkonen S, Koskimies AI, Tenhunen A, Ylostalo P: Diagnosis of luteinized unruptured follicle (LUF) syndrome by ultrasound. Fertil Steril41:26, 1984 15. Daly DC, Soto-Albors C, Walters C, Ying Y, Riddick DH: Ultrasonographic assessment of luteinized unruptured follicle syndrome in unexplained infertility. Fertil Steril 43: 62,1985 16. Eissa MK, Sawers RS, Docker MF, Lynch SS, Newton JR: Characteristics and incidence of dysfunctional ovulation patterns detected by ultrasound. Fertil Steril47:603, 1987 17. Coutts JRT, Gaukroger JM, Samad-Kader A, Macnaughton MC: Steroidogenesis by the human Graafian follicle. In Functional Morphology of the Human Ovary, Edited by JRT Coutts. Lancaster, MTP Press, 1981, p 53 18. Carr BR, Sadler RK, Rochelle DB, Stalmach MA, Macdonald PC, Simpson ER: Plasma lipoprotein regulation of progesterone biosynthesis by human corpus luteum tissue in organ culture. J Clin Endocrinol Metab 52:875, 1981 19. Hillier SG, Wickings EJ: Cellular aspects of corpus luteum function. In The Luteal Phase, Edited by SL Jeffcoate. London, John Wiley, 1985, pI 20. McLachlan RI, Robertson DM, Healy DL, Burger HG, De Kretser DM: Circulating immunoreactive inhibin levels during the normal human menstrual cycle. J Clin Endocrinol Metab 65:954, 1987 21. Di Zerega GS, Hodgen GD: Luteal phase dysfunction infertility: a sequel to aberrant folliculogenesis. Fertil Steril 35: 489,1981 22. Stouffer RL, Hodgen GD, Ottobre AC, Christian CD: Follicular fluid treatment during the follicular versus luteal phase of the menstrual cycle: effects on corpus luteum function. J Clin Endocrinol Metab 58:1027,1984 23. Stanger JD, Yovich JL: Failure of human oocyte release at ovulation. Fertil Steril41:827, 1984 24. De Crespigny LCh, O'Herlihy C, Robinson HP: Ultrasonic observation of the mechanisms of human ovulation. Am J Obstet Gynecol139:636, 1981
Hamilton et aI.
Luteal cyst formation
37
FERTILITY AND STERILITY Copyright ~ 1990 The American Fertility Society
Printed on acid-free paper in U.S.A.
Luteal cysts and unexplained infertility: biochemical and ultrasonic evaluation*
Mark P. R. Hamilton, M.D.t:j:§ Richard Fleming, Ph.D.t John R. T. Coutts, Ph.D.t
Malcolm C. Macnaughton, M.D.t Charles R. Whitfield, M.D.§
University of Glasgow, Glasgow, Scotland
A prospective, controlled study of ovarian function using ovarian ultrasound and daily plasma hormone estimations (estradiol, progesterone [P], follicle-stimulating hormone [FSH], luteinizing hormone [LH]) was carried out on 175 spontaneously cycling patients with unexplained infertility. Forty-one (23.4%) demonstrated luteal phase cyst formation. In 21 cycles the dominant follicle reduced in size after the LH peak (cystic corpus luteum cycles), and in 20 no shrinkage was seen (luteinized unruptured follicles). Progesterone concentrations in the early luteal phase were significantly reduced in the luteinized unruptured follicle cycles. Elevation in plasma FSH was seen in the early follicular and luteal phases of both cyst forming groups and may be due to disturbances in ovarian metabolism. Follicular rupture is important for efficient P release by the corpus luteum. Fertil Steril 54:32, 1990
The assumptions that ovulation is an inevitable consequence of a luteinizing hormone (LH) surge and that a "normal" plasma progesterone (P) Concentration is always associated with ovulation have been questioned for some time. That infertility might be a consequence of repeated oocyte entrapment within an unruptured follicle, in the presence of biochemical and endometrial evidence of "normal ovulation," has also been a matter of considerable speculation. 1-3 The concept of a luteinized unruptured follicle has been explored extensively using laparoscopy4 and analyses of peritoneal fluid ovarian steroids. 5 In addition, ovarian ultrasound (US) provides a direct means of evaluation of ovarian function. 6,7 In
the normal cycle, the dominant follicle shrinks and becomes infilled after the LH peak, but, in a proportion of cases, its cystic nature can be seen to persist during the luteal phase. 7,8 The use of ovarian US to define the luteinized unruptured follicle syndrome, both in stimulated9-11 and unstimulated cycles,12-15 has been used extensively. Understanding the pathogenesis of these phenomena has been hampered through lack of numbers,9,12 variation in the US criteria for the diagnosis of luteinized unruptured follicle syndrome, failure to relate the observations to biochemical indices of pituitary and ovarian function,8,10,13-15 and lack of uniformity of the patients under study. 11,16
Received November 13, 1989; revised and accepted March 13, 1990. * Supported by grant G8200415 SB from the Medical Research Council, London, United Kingdom. t Department of Obstetrics and Gynaecology. :j: Reprint requests: Mark P.R. Hamilton, M.D., Department of Obstetrics and Gynaecology, Royal Infirmary, Alexandra Parade' Glasgow G312ER, Scotland. § Department of Midwifery.
The present study was designed to effect longitudinal assessments of ovarian function prospectively in a large population of women with unexplained infertility. Repeated US evaluations offollicular growth profiles were compared with suitable controls, and the incidence and natural history of US observed luteal phase cysts were determined. The relationships of these phenomena to pituitary and ovarian hormone profiles were analyzed to
32
Hamilton et al.
Luteal cyst formation
Fertility and Sterility
study the possible pathogenic mechanisms involved in the US abnormalities seen. MATERIALS AND METHODS
ceptive use over the previous 6 months; and no sexual activity during the cycle of investigation. The age of the controls ranged from 18 to 36 years (median 26 years).
Patients and Blood Samples
Analyses and Statistics
The study group comprised 175 patients with >3 years unexplained infertility-normal menstrual rhythm (cycle length 24 to 41 days), normallaparoscopy within the previous 2 years, male partner normal, normal postcoital test, and no sexual problems. All underwent a fixed protocol of investigation. A blood sample (10 mL) was taken from every patient at the same time of day throughout the entire menstrual cycle and each plasma separated and stored at -20°C for retrospective analyses. Sensitive, specific, and precise radioimmunoassays for 17/3-estradiol (E 2 ), P, LH, and follicle-stimulating hormone (FSH) were carried out on all samplesP Samples from a complete cycle were analyzed in a single batch to eliminate the effects of interassay variations when evaluating a single profile.
The cycles were organized around the day of the LH peak (day 0). Days before this (follicular phase) were denoted negative, and days after this (luteal phase) were denoted positive. A P index was calculated for the area under the curve of P concentrations in the early luteal phase of each cycle. This index was the sum of all P values from days +2 to +6 in the study cycle, expressed as a percentage of the mean of the control population P concentrations over the same period. No assumption was made regarding the distribution of the data in respect to the study and control cycles, and, except where indicated, a nonparametric method of statistical analysis (Wilcoxon rank sum test) was employed to determine differences between groups.
Ultrasound Scans
Luteal cyst formation was diagnosed when a cystic structure was observed, between days +5 and +8, in the ovary that had contained the dominant follicle. The diameters of the cysts were calculated on the basis of the mean of all diameters measured between days +5 and +8.
Scans were performed by a single operator (M.P.R.H.) using a B-mode static scanner (Nuclear Enterprises 4201, Fischer, Edinburgh, Scotland) with a 3.5 MHz probe, calibrated to 1,540 m/s. The full bladder technique permitted visualization of the developing Graafian follicle, which was measured in three dimensions, follicular diameter being expressed as a mean of these three measurements. Scans were carried out from the 8th day ofthe cycle onward. Once identified, the developing follicle was monitored through daily scans until the characteristic infilling as it became a corpus luteum (CL) was observed. All patients underwent at least three US examinations in the luteal phase, and if a cystic structure persisted in the ovary, US monitoring continued at 48 hourly intervals until menstruation ensued. Controls
Forty-three women of reproductive age volunteered to undergo investigation using a similar protocol of blood samples and US scans. Criteria for inclusion were: normal menstrual rhythm (24 to 41 days) over the preceding 6 months; no past history of gynecological disease; no history of oral contraVol. 54, No.1, July 1990
Definition of Luteal Cyst
RESULTS
Forty-one (23.4%) of the 175 patients under study showed luteal cyst formation. Median age of these patients was 29 years (range 22 to 39 years), similar to the rest of the unexplained infertile population. Median follicular phase duration (1st day of menses up to and including day 0) was 14 days (range 8 to 27 days), and luteal phase length (day +1 to day before onset of next period inclusive) ranged from 11 to 18 days (median 15 days). These cycle characteristics were similar to those of the control population. None of the 43 control cycles showed luteal cyst formation (x 2 = 12.41, P < 0.0001). Frequent scanning during the periovulatory period permitted discrimination between those cycles where the dominant follicle was seen to reduce in size immediately after the LH peak (21 cycles [51.2% of the cyst group]), and those where Hamilton et at.
Luteal cyst formation
33
Table 1 Luteal Cyst Formation in Patients With Unexplained Infertility (n = 175)
Group
Percentage of cysts
No.
Cyst formers Large cysts (>20 mm) Small cysts «20 mm) Shrinkers Nonshrinkers
41 30 11 21 20
240 200
Percentage of series 23.4 17.1 6.3 12.0 11.4
100.0 73.2 26.8 51.2 48.8
E2
160 120
o the dominant follicle showed no evidence of shrinkage after day 0 (20 cycles [48.8%]) (Table 1). Figures 1, 2, 3, 4, and 5 detail the follicular diameter, E 2 , P, FSH, and LH data relating to these subgroups of cyst formers, i.e., shrinkers and nonshrinkers. The median values in both groups are plotted against the 95% confidence limits of the control data, represented by the shaded area on each graph. Statistical significance, where found, in comparison between the groups and also with the control data, is presented. Follicular Diameters
There was no difference (Fig. 1) between the two study groups or the controls in follicular diameter profiles up to and including day O. Divergence from normal occurred from day +1 onward. Median cyst size was significantly greater in the nonshrinkage (33.0 mm) compared with the shrinkage cycles (18.5 mm, P < 0.001). An arbitrary distinction was made between large (follicular diameter> 20 mm) and small (follicular
NO SIGNIFICANT DIFFERENCES BETWEEN THE GROUPS AND IN COMPARISON WITH CONTROLS.
- 10
-5
0
5
10
15
Day relative to LH peak Figure 2 Median plasma E2 concentrations (pg/mL) (days -10 to +14) in luteal cyst cycles (shrinkers n = 21, nonshrinkers n = 20). Shaded area represents 95% confidence limits of the control population (n = 43). No significant difference (Wilcoxon rank sum test) compared with controls or between groups.
diameter < 20 mm) luteal phase cysts based on the mean diameter ofthe dominant follicle in the control cycles on day 0, i.e., 20.2 mm. Large luteal cysts were found in 30 ofthe 41 cycles (73.2%), whereas small cysts were seen in 11 cycles (26.8%) (Table 1). Ten (33.3%) of the large luteal cyst cycles exhibited shrinkage of the dominant follicle after the LH peak. 17tJ-Estradiol
The E2 profiles (Fig. 2) were virtually identical in both groups of cyst formers and no different from the controls. IIEDIAN P INDICES
25
Conlroft 1011.0 Shr/nkmlM (N.s.) Non-.hrlnk". 53.5 (p <0.0(11)
40 20 35
15
30
FD 25
P
20
10
ng/ml 5
mm.
15
O~--------r--r------------~-'r-~ i iv
- 8
- 6
i
•.
-4
-2
i i i
0
2
4
iv
i
i
I
6
8
Day relative to LH peak Figure 1 Median follicular diameters (mm) (days -6 to +8) in luteal cyst cycles (shrinkers n = 21, nonshrinkers n = 20). Shaded area represents 95% confidence limits of the control population (n = 43). Up to day 0 no significant differences (Wilcoxon rank sum test) compared with controls. Significance between the groups: i, P < 0.05; ii, P < 0.02; iii, P < 0.01; iv, P < 0.001.
34
Hamilton et al.
Luteal cyst formation
,
o
z
Y
2
4
z
w
6
8
w
10
12
14
Day relative to LH peak Figure 3 Median plasma P concentrations (ng/mL) (days 0 to + 14) in luteal cyst cycles (shrinkers n = 21, nonshrinkers n = 20). Shaded area represents 95% confidence limits ofthe control population (n = 43). Significance compared with controls (Wilcoxon rank sum test): shrinkers: a, P < 0.05; b, P < 0.02; d, P < 0.001; nonshrinkers: w, P < 0.05; x, P < 0.02; y, P < 0.01; Z, P < 0.001. Significance between groups: i, P < 0.05; ii, P < 0.02; iii, P < 0.01.
Fertility and Sterility
14
DISCUSSION
12 10
FSH
lUll
-,'
Or-~~b-C~-------------------------- I W
-10
-5
0
W I
W •
5
x
10
15
Day relative to LH peak Figure 4 Median plasma FSH concentrations (lUlL) (days -10 to +14) in luteal cyst cycles (shrinkers n = 21, nonshrinkers n = 20). Shaded area represents 95% confidence limits of the control population (n = 43). Significance compared with controls (Wilcoxon rank sum test): shrinkers: a, P < 0.05; b, P < 0.02; c, P < 0.01; nonshrinkers: w, P < 0.05; x, P < 0.02; y, P < 0.01. Significance between groups: i, P < 0.05.
Progesterone
Progesterone concentrations (Fig. 3) in the cycles where no shrinkage of the dominant follicle was seen after the LH peak were profoundly reduced (median P index 53.5) compared with the control cycles (P index 100.0, P < 0.001) and to the cycles where shrinkage of the follicle was observed (median P index 84.0, P < 0.001). Although P concentrations were reduced in the cycles showing shrinkage, the difference was not significant compared with the controls. Follicle-Stimulating Hormone
In those cycles where shrinkage of the follicle was observed (Fig. 4), FSH concentrations in the early follicular phase (days -9 to -6) were significantly higher compared with the control data. In comparison with the nonshrinkage cycles, plasma FSH also tended to be higher, though this achieved statistical significance only on day -7. Midcycle concentrations were similar to the controls in both groups. In the luteal phase, there were minor differences in both groups compared with the controls. This was more pronounced in the cycles where no shrinkage was s~en (lower P concentrations), with FSH concentrations significantly elevated in the midluteal phase (days +6 to + 10). Luteinizing Hormone
Figure 5 shows the profiles of LH in both study groups and in the controls were similar throughout the cycle. Vol. 54, No.1, July 1990
This study represents a prospective, controlled analysis of ovarian function in a large population of spontaneously cycling women with unexplained infertility. Luteal cyst formation was the most common US abnormality detected, seen in almost a quarter ofthe patients under study. In half ofthese cycles, no evidence of follicular reduction in size preceded luteal cyst formation. Associations of these US profiles with diminished plasma concentrations of P in the early luteal phase and elevated concentrations of FSH in the follicular and luteal phase have been shown. This is the first substantial evidence combining biochemical and US data on such abnormalities in a uniform population. The differing US profiles seen after the LH peak suggest that two distinct pathophysiological mechanisms may be involved in luteal cyst formation. Those cycles where no shrinkage of the dominant follicle occurred after the LH peak, and where P concentrations were profoundly reduced, may represent the luteinized unruptured follicle syndrome. The other group, where some shrinkage (rupture?) of the dominant follicle was observed, were associated with marginally reduced plasma P concentrations and could be described as cycles with cystic CL formation. The US data suggest that ovulation could have occurred in the cystic CL cycles, but since similar US profiles were not seen in the control cycles, both phenomena may indicate an infertile cycle among this subfertile population. These events could not be predicted on the basis of follicular maturation as assessed by either circulating E2 75 non - shrlnker.
60
/'
45
LH
30
lUll 15
__...
,',
a.~
, , '.
o
~
NO SIGNIFICANT DIFFERENCES BETWEEN THE GROUPS AND IN COMPARISON WITH CONTROLS
-10
- 5
0
5
10
15
Day relative to LH peak Figure 5 Median plasma LH concentrations (lUlL) (days -10 to +14) in luteal cyst cycles (shrinkers n = 21, nonshrinkers n = 20). Shaded area represents 95% confidence limits of the control population (n = 43). No significant difference (Wilcoxon rank sum test) compared with controls or between groups. Hamilton et al.
Luteal cyst formation
35
concentrations or follicular phase follicular diameter patterns, and the size of the luteal cyst did not discriminate between the two groups. Only 2 of the 20 luteinized unruptured follicle cycles were associated with a normal P index as compared with 17 of the 21 cystic CL cycles (x 2 = 20.7, P < 0.0001). These data lend support to the concept that follicular rupture is a necessity for efficient P production in the luteal phase. A previous study16 on a small, heterogeneous group of patients, a minority with unexplained infertility, described similar patterns of luteal cyst formation. Cycles demonstrating US evidence of shrinkage were described as the luteinized unruptured follicle syndrome and were associated with normal luteal phase P concentrations. Expansion of a luteal cyst after US evidence of shrinkage (seen in 10 of the 21 cystic CL cycles described in the present study) was not observed in their series. Their data contrast with our own, which suggest that luteinized unruptured follicle cycles, often associated with diminished P concentrations in the luteal phase, are characterized by follicular expansion without prior reduction in size. The role of LD L in steroid synthesis in the luteal phase 18 is well established. In the normal CL, granulosa lutein cells enjoy intimate contact with capillary blood from which they take up steroid precursors for P synthesis. Disruption of the basement membrane barrier between blood and the granulosa lutein cells is probably necessary for the initiation and maintenance of CL function. The lag in P production observed in the nonshrinkage cycles could be explained by impairment of angiogenesis after the LH surge, leading to diminished availability of steroid precursors and release of P into the circulation. In cycles with normal P indices, most of which occurred in the group demonstrating evidence of follicular shrinkage, availability of precursors in the early luteal phase was probably unaffected, despite luteal cyst formation. This provides evidence that limited US data of periovulatory follicular dynamics cannot discriminate absolutely between normal and abnormal potential for steroid production, or ovulation. There is no doubt that the human luteotrophic complex requires LH, but it is probable that other factors influence steroid biosynthesis as well. In both subgroups, FSH concentrations were found to be slightly higher than the controls in the midluteal phase. It is possible that FSH is involved in the luteotrophic influence at this point in the cycle, acting on its receptor in the granulosa cell mem36
Hamilton et al.
Luteal cyst formation
brane. 19 The finding of high luteal phase FSH concentrations in many of the luteinized unruptured follicle cycles could represent an attempt at compensation for defective luteal function, but the mediator between the ovary and the pituitary in this situation is unclear since E2 concentrations were no different from normal cycle patterns and were similar in the two groups. Circulating inhibin concentrations have been found to rise in the luteal phase ofthe normal cycle,20 and it may be hypothesized that luteal cyst formation is associated with reduced concentrations of inhibin resulting in elevated concentrations of FSH. Inhibin concentrations in cycles with cyst formation have not been evaluated. Previous publications have implicated reduced early follicular phase (perimenstrual) FSH concentrations in the pathogenesis of luteal phase deficiency.1,3,21,22 The data presented here show no relationship between these phenomena and suggest that enhancement of gonadotropin activity in the early part of the follicular phase using antiestrogens, or by administration of exogenous gonadotropins, would be of little therapeutic value. It is possible that the two groups presented here may not be as distinct as their US and biochemical patterns suggest. The process of ovum release may not always be consequent on US observed follicular shrinkage,23 and ovum entrapment may have occurred in some ofthe cycles where shrinkage of the dominant follicle was observed. Conversely, in some of the non shrinking cyst formers, it is possible that a diminution in the size of the follicle might have been missed in the periods between US observations. This type of error was kept to a minimum by the endeavor to scan patients every day over the periovulatory period. However, it is possible, since the processes of follicular rupture as observed ultrasonically take place over a relatively short period of time, 24 that some overlap of the two groups of cycles occurred. The difference in P profiles of the two groups is circumstantial evidence that the discrimination is accurate and real. In conclusion, it has been shown that although there is a close relationship between US and hormonal assessment of CL function, definition of luteal phase abnormalities requires consideration of biochemical and US indices together, rather than independently. Cycles with luteal cyst formation do not represent a homogeneous population, and the ultimate size of the cyst is not a sensitive indicator of the nature of the structure or its relationship with CL hormone output. Shrinkage of the Fertility and Sterility
dominant follicle before cyst formation appears to be a major determining factor of the steroidogenic potential of the luteinized follicle but may not be the only one. The effect on fecundity of luteal phase deficiency can possibly be explained by three mechanisms: failure of oocyte release, abnormal follicular metabolism, and potential disturbances in endometrial receptivity mediated through diminished circulating P concentrations. Continued infertility is most likely due to the frequency with which such disturbances recur. Acknowledgments. The assistance of the laboratory staff of the Department of Obstetrics and Gynaecology, Royal Infirmary, Glasgow, and ofthe staff ofthe Department of Ultrasonic Technology, Queen Mother's Hospital, Glasgow, is gratefully acknowledged.
REFERENCES 1. Sherman BM, Korenman SG: Measurement of plasma LH, FSH, estradiol and progesterone in disorders of the human menstrual cycle: the inadequate luteal phase. J Clin Endocrinol Metab 39:145,1974 2. Jewelewicz R: Management of infertility resulting from anovulation. Am J Obstet Gynecol122:909, 1975 3. Jones GS, Maffezoli RD, Strott GA, Ross GT, Kaplan G: Pathophysiology of reproductive failure after clomiphene induced ovulation. Am J Obstet Gynecol108:84 7, 1970 4. Koninckx PR, Heyns WJ, Corvelyn PA, Brosens IA: Delayed onset of luteinization as a cause of infertility. Fertil Steril 29:266, 1978 5. Devroey P, Temmerman M, Verhoeven N, Naaktgeboren N, Heip J, Amy JJ, Van Steirteghem AC: Recurrence ofthe luteinized unruptured follicle. Br J Obstet Gynaeco190:381, 1983 6. Hackeloer BJ, Fleming R, Robinson HP, Adam AH, Coutts JRT: Correlation of ultrasonic and endocrinologic assessment of human follicular development. Am J Obstet Gynecol 135:122, 1979 7. Queenan JT, O'Brien GD, Bains LM, Simpson J, Collins WP, Campbell S: Ultrasound scanning of ovaries to detect ovulation in women. Fertil Steril34:99, 1980 8. Nitschke-Dabelstein S, Hackeloer BJ, Sturm G: Ovulation and corpus luteum formation observed by ultrasonography. Ultrasound Med BioI 7:33, 1981 9. Coulam CB, Hill LM, Breckle R: Ultrasonic evidence for luteinization of unruptured preovulatory follicles. Fertil Steril 37:524, 1982
Vol. 54, No.1, July 1990
10. Gibbons WE, Buttram VC, Jr, Rossavik IK: The observed incidence of luteinized unruptured follicles in a population of infertile women undergoing ovulation monitoring by ultrasound. (Abstr. 44) Fertil Steril41:19S, 1984 11. Hamilton CJCM, Wetzels LCG, Evers JLH, Hoogland HJ, Muijtjens A, de Haan J: Follicle growth curves and hormonal patterns in patients with the luteinized unruptured follicle syndrome. Fertil Steril43:541, 1985 12. Coutts JRT, Adam AH, Fleming R: The deficient luteal phase may represent an anovulatory cycle. Clin Endocrinol (Oxf) 17:384,1982 13. Kerin JF, Kirby C, Morris D, McEvoy M, Ward B, Cox LW: Incidence of the luteinized unruptured follicle phenomenon in cycling women. Fertil Steril 40:620, 1983 14. Liukkonen S, Koskimies AI, Tenhunen A, Ylostalo P: Diagnosis of luteinized unruptured follicle (LUF) syndrome by ultrasound. Fertil Steril41:26, 1984 15. Daly DC, Soto-Albors C, Walters C, Ying Y, Riddick DH: Ultrasonographic assessment of luteinized unruptured follicle syndrome in unexplained infertility. Fertil Steril 43: 62,1985 16. Eissa MK, Sawers RS, Docker MF, Lynch SS, Newton JR: Characteristics and incidence of dysfunctional ovulation patterns detected by ultrasound. Fertil Steril47:603, 1987 17. Coutts JRT, Gaukroger JM, Samad-Kader A, Macnaughton MC: Steroidogenesis by the human Graafian follicle. In Functional Morphology of the Human Ovary, Edited by JRT Coutts. Lancaster, MTP Press, 1981, p 53 18. Carr BR, Sadler RK, Rochelle DB, Stalmach MA, Macdonald PC, Simpson ER: Plasma lipoprotein regulation of progesterone biosynthesis by human corpus luteum tissue in organ culture. J Clin Endocrinol Metab 52:875, 1981 19. Hillier SG, Wickings EJ: Cellular aspects of corpus luteum function. In The Luteal Phase, Edited by SL Jeffcoate. London, John Wiley, 1985, pI 20. McLachlan RI, Robertson DM, Healy DL, Burger HG, De Kretser DM: Circulating immunoreactive inhibin levels during the normal human menstrual cycle. J Clin Endocrinol Metab 65:954, 1987 21. Di Zerega GS, Hodgen GD: Luteal phase dysfunction infertility: a sequel to aberrant folliculogenesis. Fertil Steril 35: 489,1981 22. Stouffer RL, Hodgen GD, Ottobre AC, Christian CD: Follicular fluid treatment during the follicular versus luteal phase of the menstrual cycle: effects on corpus luteum function. J Clin Endocrinol Metab 58:1027,1984 23. Stanger JD, Yovich JL: Failure of human oocyte release at ovulation. Fertil Steril41:827, 1984 24. De Crespigny LCh, O'Herlihy C, Robinson HP: Ultrasonic observation of the mechanisms of human ovulation. Am J Obstet Gynecol139:636, 1981
Hamilton et aI.
Luteal cyst formation
37