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The primigravida in labor with high fetal station
The primigravida A study of 1,209 hospital
CHARLES Seattle,
G.
in labor with high fetal station
records
STIPP,
of obstetric
patients
M.D.
Washington
It is generally accepted that high fetal station in primigravidas in labor near term may indicate a threat to the normal progress of labor because of fetopelvic disproportion or obstruction of the fetal passageway by tumors or the placenta. The hospital records of 1,209 obstetric patients were reviewed and 430 primigravidas were selected for detailed study by including only those with vertex presentations that entered the hospital in labor the thirty-eighth week of gestation or later. These patients were further divided into two groups, those with engaged fetal heads and those with unengaged fetal heads. When these two groups were compared, no statistical difference was found in the length of the first and second stages of labor, method of delivery, fetal head position, weight of the infant, or Apgar rating.
1 T I s G E N E R A L L Y accepted that high fetal station in primigravidas in labor near term may indicate a threat to the normal progress of labor because of fetopelvic disproportion or obstruction of the fetal passageway by tumor or the placenta. Engagement, by definition, is that point near term when the biparieta1 diameter of the fetal head descends to the inlet of the maternal pelvis. Labor, for the purpose of this paper, is defined as regularly occurring uterine contractions that produce cervical dilatation, eventually culminating in a delivery during this hospitalization. Caldwell and Moloy,” in 1934, studied and defined the mechanism of engagement of the fetal head with respect to the shape of the maternal inlet by taking stereoroentgenograms of primigravidas in early labor. In 1949, Auer and Simmons* analyzed a selected series of their own primigravid pa-
From the Department of Obstetrics Gynecology, The Swedish Hospital Medical Center.
tients. They found that more than one third of those that reached term with unengaged heads had midpelvic contracture. Although their cesarean section rate was 24 per cent, they felt that a higher rate would have avoided many difficult deliveries. The purpose of this paper is to present data on this subject gathered from a large metropolitan hospital. --Material
and
methods
Basic obstetric data were obtained from the hospital records of 1,209 consecutive obstetric patients at the Swedish Hospital Medical Center. These data were recorded on standard punch cards and stored in an IBM 360 Model 65 computer. The data were retrieved through the Praline Program designed especially for questionnaire analysis. All data were subjected to chi square analyses to determine statistical significance and the null hypothesis was rejected at the level of 0.05 probability and above. In the original group of patients there were 482 primigravidas and 725 multiparas. Two hospital records stated no parity. The youngest patient in the study was 13 years old and the oldest was 46 years old, with the mean age being 25.9. From the original sampling, 430 primigravidas were selected
and
Supported in part by a grant from the Parke, Davis 6’ Company. Presented by invitation at the Thirtyfifth Annual Meeting of the Pacific Coast Obstetrical and Gynecological Society, Gteneden Beach, Oregon, Oct. 2-5, 1968.
267
for detailed study by including only those with vertex presentations that entered the hospital in labor the thirty-eighth lveek of gestation or later. These patients were further divided into two groups: Group A included all selected primigravidas who entered the hospital with engaged fetal heads; Group B included all selected prirnigravidas who entered the hospitni \vitIl unenaged fetal heads. .4t the time of the patient’s admittance to the hospital, engagement 01 lack of engagement was determined by vaginal examination by the attending obstetrician or by the obstetric resident. In some instances this examination was done rectally by trained obstetric nurses.
Table
I. Length
of the first stage of iabol
Table
II. Length
of the second stage of labor ___._~~ ~. Group
Minutes
Results Fetal encasement had taken alacr in 193 (44.8 per cent) (Group A), while 237 primigravidas (55.2 per cent) entered thr hospital in labor with unengaged fetal heads (Group 13). Y”
1
Clinical peIvimetry was done prenatally by the obstetrician in 91.7 per cent of all cases and 88.4 per cent of these were judged to be adequate, but among those selected primigravidas who entered the hospital with unengaged fetal heads, cl inical pelvimetry was not done in 5.9 per cent. The pelves were not classified as to type in 74.6 per cent of all patients. In Group A, those with engaged fetal heads, 91 per cent were found to have cervical dilatation of 2 cm. or more on admission to the hospital; while in Group B. with unengaged fetal heads. 25 per cent were only 1 cm. dilated on admission to the hospital. Two patients of the unengaged group entered the hospital at 8 cm. dilatation. Oxytocin was used to augment labor in 23 patients in Group A ( 11.9 per cent\ as compared with 46 patients ( 19.4 per cent) in Group B. While the difference is not statistically significant, an increase of 63 prr cent of patients with unengaged fetal heads needed augmentation of their labor with oxytocin. Table I compares the length of the first stage of labor in the two groups. The results
No.
O-5 6-10 11-20 ‘l-30 31-60 61-1’20
over
120
Cesarean section Not stated Total
Table
III.
Group No.
1.6 1.0 11.9 15.0 25.9 26.4 17.6 0.5 0 100.0
3 5 “7 2.“7 57 62 48 11 1 237
TrCZnJ/ irerse
j
B ‘;h, 1 ..3 2. I 11.4 9.! ‘3.1 26.2 20.3 -I .ii 0.4 100.0
.- _--..
Pm/ terior
I Not / .stated
“I) 10.4
3 1.5
193 100.0
16 6.7
237 100.0
1 Total
A 158 81.9
PiO.
% Croup No. %,
3 ‘1 29 29 50 51 34 1 0 193
A :4,
Fetal presentation _---.--i----.--’ An/ terior
Croup
1
12 6.2
B __-
~--
similar in all categories except the 13 to 18 hour group. where a difference of 4.7 per cent was encountered in Group B (those patients with unengaged heads). This difference is not statistically significant. Table II demonstrates the similarity of the length of the second stage of labor in the two groups. X-ray pelvimetry was performed on onl) 5 patients (2.6 per cent’1 in Group A, and in 20 instances (8.5 per cent) in Group R. The differences were statistically insignifiare
Volume 104 Number
High fetal station in primigravida in labor
2
Spontaneous Group NO. 5% Group No. 70
Low
forceps
Midforceps
stated
Total
16 8.3
144 74.6
30 15.6
1 0.5
2 1.0
193 100.0
16 6.8
173 73.0
35 14.8
12 5.1
1 0.4
237 100.0
B
of the baby Croup
Pounds
No.
9
Table VI.
Apgar
score
70
No.
B (
7~
4
1.7
12
5.1
53 81 34 6
8.8 27.5 42.0 17.6 3.1
29 96 53 12
0 193
0 100.0
24.9 40.5 22.4 5.1 0.4
rating Group
1 2
Group
A
1.0 1:
Not stated Total
Apgar
Not
A
Table V. Weight
o-5 5-6 6-7 7-8 8-9 Over
Cesarean section
269
No.
0 1 1 1
3 4 5 6 7 8 9
4 1 12 39 112
10 Not stated Total
9 13 193
100.0-
23:
at one minute A
70 0
Group
B -
(
No.
0 1
7% 0
0.5 0.5 0.5 2.1 it;
3 4 1:
0.4 1.3 1.7 3.8 4.6
20.2 58.0 4.7 6.7
26 41 117 7 18 237
17.3 49.4 3.0 7.6
100.0
11.0
100.0-
cant. Among these 20 patients, in all but 5 instances the pelvis was roentgenologically normal. In 5 patients it was considered of borderline dimensions. The position of the fetal head was examined to see if different positions influenced either of the groups. Table III presents these results. The differences were statistically insignificant. The method of delivery is presented in Table IV. In this study 94.6 per cent of those
delivered vaginally. This is higher than in the Auer and Simmons series,l where only 74 per cent were delivered vaginally. The use of midforceps was actually more frequent among those patients with engaged heads than those with unengaged heads, although the figures are not statistically significant. Of the 12 cesarean sections done in Group B, the patients with unengaged fetal heads, 7 were done for cephalopelvic disproportion. Three were performed for uterine dystocia, and one each for cervical dystocia and abruptio placentae. X-ray pelvimetry was obtained in all but one of these patients, and pelvic dimensions were considered adequate in all those that were done. Weight of the infant at delivery is presented in Table V. Although it appears on the surface that a substantially greater number of infants with unengaged heads weighed 8 pounds or more, this difference when submitted to statistical study was found to be insignificant. Apgar ratings at one minute are presented in Table VI. While some difference is apparently noted between the numbers in the two groups of infants with Apgar 6 or 7, these differences are not significant as determined by chi square values. Comment Although many obstetricians believe that high fetal station in primigravidas in labor near term is a threat to the normal progress of labor, the results of this study should help to allay their fears, in that 94:6 per cent of this group were delivered vaginally. In com-
unengaged fetal heads with those that entered the hospital with engaged fetal heads, no statistical difference was found in the length of the first and second stages of labor, method of delivery, fetal head position, weight of the infant, or the Apgar rating. The cesarean section rate was higher in the unengaged fetal head group, apparently due to cervical or uterine dystocia. It is interesting to speculate on the indication for cesarean section among the 7 patients with unengaged fetal heads who had a diagnosis of cephalopelvic disproportion, but with roentgenologically normal pelves. Perhaps the implication of the un-
engaged fetal head in a primigravicla in a few instances has led to the acceptance of the state of disproportion Lvithout confirming support by s-ray or clinical mensuration of the pelvis. While it is often tempting to view yross differences in numerical results that support our pre-existing concepts of the significance of the unengaged fetal head, if MC’ art’ to be medically honest lve must view these differences in the light of statistical probabilit? and agree that if they fail the test of siqnificance, we Inay merely bc s&ng the IV suits of sampling frequency.
REFERENCES
1. Auer,
and Simmons. J. M.: Aar. J. 58: 291. 1949. Burke, L., Rubin, H. w., and Berenbrrg, A. 76: 132, 1958. L.: AM. J. OBST. & GYNEC. Caldwell, W. E., and Moloy, H. C.: AM. J. OBST. & GYNEC. 28: 824, 1934. Calkins, L. A.: AM. J. OBST. & GYNEC. 48: 789, 1948. OBST.
2. 3. 4.
E.
S.,
Discussion DR. HOWARD California. Every
doctor
asked
sciously, Will canal safely?
conditions
JR.,*
HAMMOND,
time
himself the The
a patient
San Kafael, is in labor, her
consciously
or
uncon-
baby come through the birth answer depends on multiple
and Dr. Stipp has today discussed one
of these factors: The high fetal station in primigravida during labor. He has analyzed 430 cases of primigravidas in labor showing that 55.2 per cent entered
the
*By
as these other authors, yet only 44.8 were engaged. Why is there such a difwho was Dr. Stipp’s profesCalkinq3
invitation.
6. 7.
Davies, J. W., and Renning, E.: West. J. Surg. 66: 61, 1958. Friedman, E. A., and Sachtleben, M. R.: .\,I. J. OBST. & GYNEC. 93: 522, 1965. Menpert, F. W.: J. .4. M. .4. 138: 169: 1948. 1018 Summit Avenue Seattle, Washington 981 O+
ser. said the etiology of the high station in most cases was due to the retvix and the IONCI utprinr segment. Disproportion, due to a small pelvis or a large baby, placental position: ab-
normal presentation, or tumor are other reasons. None of the latter factors is identified as a caustx for these 55 per cent of unengaged heads, rvhich must mean that the cervix and lower utrrinc se,gmmt in Seattle are tougher than in Baltimore
or Denver. the
hospital with unengaged fetal heads and 44.8 per cent with engaged fetal heads. In comparing these two groups there were no statistically valid differences in the length of labor, method of delivery, weight of the baby, or Apgar rating. Eastman and Hellman] state a much different percentage of engaged heads under these conditions, giving 90 per cent engagement as normal. Auer and Simmons? gave 91.3 per cent. Dr. Stipp has used the same definitions for engagement per cent ference?
5.
& GYNEC.
Obstetricians generally feel that an unrngaged hc>ad in a primigravida at the onset of labor always calls for careful re-evaluation of tht% whole cephalopelvic interrelationship.1 In Stipp’s
series we would
1~ concerned
about 55 per crnt
of all primigravidas brcause of this one factor alone, whereas Auer and Simmons considered this factor in only 10 per cent or less. Comparison of the cesarean section ralcs of Stipp and Auer and Simmons shows an interesting method of using figures. Auer and Simmons hid a 24 per cent cesarean rate in thrir unengaged series, whereas Stipp’s was ahout 5 prr cent. This is almost a 5 to 1 difference, but also the same difference in reverse as their rates of unengagement : 55 per cent to 10 per cent.
CHARLES Seattle,
G.
in labor with high fetal station
records
STIPP,
of obstetric
patients
M.D.
Washington
It is generally accepted that high fetal station in primigravidas in labor near term may indicate a threat to the normal progress of labor because of fetopelvic disproportion or obstruction of the fetal passageway by tumors or the placenta. The hospital records of 1,209 obstetric patients were reviewed and 430 primigravidas were selected for detailed study by including only those with vertex presentations that entered the hospital in labor the thirty-eighth week of gestation or later. These patients were further divided into two groups, those with engaged fetal heads and those with unengaged fetal heads. When these two groups were compared, no statistical difference was found in the length of the first and second stages of labor, method of delivery, fetal head position, weight of the infant, or Apgar rating.
1 T I s G E N E R A L L Y accepted that high fetal station in primigravidas in labor near term may indicate a threat to the normal progress of labor because of fetopelvic disproportion or obstruction of the fetal passageway by tumor or the placenta. Engagement, by definition, is that point near term when the biparieta1 diameter of the fetal head descends to the inlet of the maternal pelvis. Labor, for the purpose of this paper, is defined as regularly occurring uterine contractions that produce cervical dilatation, eventually culminating in a delivery during this hospitalization. Caldwell and Moloy,” in 1934, studied and defined the mechanism of engagement of the fetal head with respect to the shape of the maternal inlet by taking stereoroentgenograms of primigravidas in early labor. In 1949, Auer and Simmons* analyzed a selected series of their own primigravid pa-
From the Department of Obstetrics Gynecology, The Swedish Hospital Medical Center.
tients. They found that more than one third of those that reached term with unengaged heads had midpelvic contracture. Although their cesarean section rate was 24 per cent, they felt that a higher rate would have avoided many difficult deliveries. The purpose of this paper is to present data on this subject gathered from a large metropolitan hospital. --Material
and
methods
Basic obstetric data were obtained from the hospital records of 1,209 consecutive obstetric patients at the Swedish Hospital Medical Center. These data were recorded on standard punch cards and stored in an IBM 360 Model 65 computer. The data were retrieved through the Praline Program designed especially for questionnaire analysis. All data were subjected to chi square analyses to determine statistical significance and the null hypothesis was rejected at the level of 0.05 probability and above. In the original group of patients there were 482 primigravidas and 725 multiparas. Two hospital records stated no parity. The youngest patient in the study was 13 years old and the oldest was 46 years old, with the mean age being 25.9. From the original sampling, 430 primigravidas were selected
and
Supported in part by a grant from the Parke, Davis 6’ Company. Presented by invitation at the Thirtyfifth Annual Meeting of the Pacific Coast Obstetrical and Gynecological Society, Gteneden Beach, Oregon, Oct. 2-5, 1968.
267
for detailed study by including only those with vertex presentations that entered the hospital in labor the thirty-eighth lveek of gestation or later. These patients were further divided into two groups: Group A included all selected primigravidas who entered the hospital with engaged fetal heads; Group B included all selected prirnigravidas who entered the hospitni \vitIl unenaged fetal heads. .4t the time of the patient’s admittance to the hospital, engagement 01 lack of engagement was determined by vaginal examination by the attending obstetrician or by the obstetric resident. In some instances this examination was done rectally by trained obstetric nurses.
Table
I. Length
of the first stage of iabol
Table
II. Length
of the second stage of labor ___._~~ ~. Group
Minutes
Results Fetal encasement had taken alacr in 193 (44.8 per cent) (Group A), while 237 primigravidas (55.2 per cent) entered thr hospital in labor with unengaged fetal heads (Group 13). Y”
1
Clinical peIvimetry was done prenatally by the obstetrician in 91.7 per cent of all cases and 88.4 per cent of these were judged to be adequate, but among those selected primigravidas who entered the hospital with unengaged fetal heads, cl inical pelvimetry was not done in 5.9 per cent. The pelves were not classified as to type in 74.6 per cent of all patients. In Group A, those with engaged fetal heads, 91 per cent were found to have cervical dilatation of 2 cm. or more on admission to the hospital; while in Group B. with unengaged fetal heads. 25 per cent were only 1 cm. dilated on admission to the hospital. Two patients of the unengaged group entered the hospital at 8 cm. dilatation. Oxytocin was used to augment labor in 23 patients in Group A ( 11.9 per cent\ as compared with 46 patients ( 19.4 per cent) in Group B. While the difference is not statistically significant, an increase of 63 prr cent of patients with unengaged fetal heads needed augmentation of their labor with oxytocin. Table I compares the length of the first stage of labor in the two groups. The results
No.
O-5 6-10 11-20 ‘l-30 31-60 61-1’20
over
120
Cesarean section Not stated Total
Table
III.
Group No.
1.6 1.0 11.9 15.0 25.9 26.4 17.6 0.5 0 100.0
3 5 “7 2.“7 57 62 48 11 1 237
TrCZnJ/ irerse
j
B ‘;h, 1 ..3 2. I 11.4 9.! ‘3.1 26.2 20.3 -I .ii 0.4 100.0
.- _--..
Pm/ terior
I Not / .stated
“I) 10.4
3 1.5
193 100.0
16 6.7
237 100.0
1 Total
A 158 81.9
PiO.
% Croup No. %,
3 ‘1 29 29 50 51 34 1 0 193
A :4,
Fetal presentation _---.--i----.--’ An/ terior
Croup
1
12 6.2
B __-
~--
similar in all categories except the 13 to 18 hour group. where a difference of 4.7 per cent was encountered in Group B (those patients with unengaged heads). This difference is not statistically significant. Table II demonstrates the similarity of the length of the second stage of labor in the two groups. X-ray pelvimetry was performed on onl) 5 patients (2.6 per cent’1 in Group A, and in 20 instances (8.5 per cent) in Group R. The differences were statistically insignifiare
Volume 104 Number
High fetal station in primigravida in labor
2
Spontaneous Group NO. 5% Group No. 70
Low
forceps
Midforceps
stated
Total
16 8.3
144 74.6
30 15.6
1 0.5
2 1.0
193 100.0
16 6.8
173 73.0
35 14.8
12 5.1
1 0.4
237 100.0
B
of the baby Croup
Pounds
No.
9
Table VI.
Apgar
score
70
No.
B (
7~
4
1.7
12
5.1
53 81 34 6
8.8 27.5 42.0 17.6 3.1
29 96 53 12
0 193
0 100.0
24.9 40.5 22.4 5.1 0.4
rating Group
1 2
Group
A
1.0 1:
Not stated Total
Apgar
Not
A
Table V. Weight
o-5 5-6 6-7 7-8 8-9 Over
Cesarean section
269
No.
0 1 1 1
3 4 5 6 7 8 9
4 1 12 39 112
10 Not stated Total
9 13 193
100.0-
23:
at one minute A
70 0
Group
B -
(
No.
0 1
7% 0
0.5 0.5 0.5 2.1 it;
3 4 1:
0.4 1.3 1.7 3.8 4.6
20.2 58.0 4.7 6.7
26 41 117 7 18 237
17.3 49.4 3.0 7.6
100.0
11.0
100.0-
cant. Among these 20 patients, in all but 5 instances the pelvis was roentgenologically normal. In 5 patients it was considered of borderline dimensions. The position of the fetal head was examined to see if different positions influenced either of the groups. Table III presents these results. The differences were statistically insignificant. The method of delivery is presented in Table IV. In this study 94.6 per cent of those
delivered vaginally. This is higher than in the Auer and Simmons series,l where only 74 per cent were delivered vaginally. The use of midforceps was actually more frequent among those patients with engaged heads than those with unengaged heads, although the figures are not statistically significant. Of the 12 cesarean sections done in Group B, the patients with unengaged fetal heads, 7 were done for cephalopelvic disproportion. Three were performed for uterine dystocia, and one each for cervical dystocia and abruptio placentae. X-ray pelvimetry was obtained in all but one of these patients, and pelvic dimensions were considered adequate in all those that were done. Weight of the infant at delivery is presented in Table V. Although it appears on the surface that a substantially greater number of infants with unengaged heads weighed 8 pounds or more, this difference when submitted to statistical study was found to be insignificant. Apgar ratings at one minute are presented in Table VI. While some difference is apparently noted between the numbers in the two groups of infants with Apgar 6 or 7, these differences are not significant as determined by chi square values. Comment Although many obstetricians believe that high fetal station in primigravidas in labor near term is a threat to the normal progress of labor, the results of this study should help to allay their fears, in that 94:6 per cent of this group were delivered vaginally. In com-
unengaged fetal heads with those that entered the hospital with engaged fetal heads, no statistical difference was found in the length of the first and second stages of labor, method of delivery, fetal head position, weight of the infant, or the Apgar rating. The cesarean section rate was higher in the unengaged fetal head group, apparently due to cervical or uterine dystocia. It is interesting to speculate on the indication for cesarean section among the 7 patients with unengaged fetal heads who had a diagnosis of cephalopelvic disproportion, but with roentgenologically normal pelves. Perhaps the implication of the un-
engaged fetal head in a primigravicla in a few instances has led to the acceptance of the state of disproportion Lvithout confirming support by s-ray or clinical mensuration of the pelvis. While it is often tempting to view yross differences in numerical results that support our pre-existing concepts of the significance of the unengaged fetal head, if MC’ art’ to be medically honest lve must view these differences in the light of statistical probabilit? and agree that if they fail the test of siqnificance, we Inay merely bc s&ng the IV suits of sampling frequency.
REFERENCES
1. Auer,
and Simmons. J. M.: Aar. J. 58: 291. 1949. Burke, L., Rubin, H. w., and Berenbrrg, A. 76: 132, 1958. L.: AM. J. OBST. & GYNEC. Caldwell, W. E., and Moloy, H. C.: AM. J. OBST. & GYNEC. 28: 824, 1934. Calkins, L. A.: AM. J. OBST. & GYNEC. 48: 789, 1948. OBST.
2. 3. 4.
E.
S.,
Discussion DR. HOWARD California. Every
doctor
asked
sciously, Will canal safely?
conditions
JR.,*
HAMMOND,
time
himself the The
a patient
San Kafael, is in labor, her
consciously
or
uncon-
baby come through the birth answer depends on multiple
and Dr. Stipp has today discussed one
of these factors: The high fetal station in primigravida during labor. He has analyzed 430 cases of primigravidas in labor showing that 55.2 per cent entered
the
*By
as these other authors, yet only 44.8 were engaged. Why is there such a difwho was Dr. Stipp’s profesCalkinq3
invitation.
6. 7.
Davies, J. W., and Renning, E.: West. J. Surg. 66: 61, 1958. Friedman, E. A., and Sachtleben, M. R.: .\,I. J. OBST. & GYNEC. 93: 522, 1965. Menpert, F. W.: J. .4. M. .4. 138: 169: 1948. 1018 Summit Avenue Seattle, Washington 981 O+
ser. said the etiology of the high station in most cases was due to the retvix and the IONCI utprinr segment. Disproportion, due to a small pelvis or a large baby, placental position: ab-
normal presentation, or tumor are other reasons. None of the latter factors is identified as a caustx for these 55 per cent of unengaged heads, rvhich must mean that the cervix and lower utrrinc se,gmmt in Seattle are tougher than in Baltimore
or Denver. the
hospital with unengaged fetal heads and 44.8 per cent with engaged fetal heads. In comparing these two groups there were no statistically valid differences in the length of labor, method of delivery, weight of the baby, or Apgar rating. Eastman and Hellman] state a much different percentage of engaged heads under these conditions, giving 90 per cent engagement as normal. Auer and Simmons? gave 91.3 per cent. Dr. Stipp has used the same definitions for engagement per cent ference?
5.
& GYNEC.
Obstetricians generally feel that an unrngaged hc>ad in a primigravida at the onset of labor always calls for careful re-evaluation of tht% whole cephalopelvic interrelationship.1 In Stipp’s
series we would
1~ concerned
about 55 per crnt
of all primigravidas brcause of this one factor alone, whereas Auer and Simmons considered this factor in only 10 per cent or less. Comparison of the cesarean section ralcs of Stipp and Auer and Simmons shows an interesting method of using figures. Auer and Simmons hid a 24 per cent cesarean rate in thrir unengaged series, whereas Stipp’s was ahout 5 prr cent. This is almost a 5 to 1 difference, but also the same difference in reverse as their rates of unengagement : 55 per cent to 10 per cent.