- Email: [email protected]
Etiology of hemorrhage in placenta previa
ETIOLOGY
OF HEMORRHAGE DAVID
(From the Departmentof
FINDLEY, Obstetrics
IN PLACENTA
M.D., and
OMAHA,
Gynecology,
PREVIA*
NEB.
University of Nebraska,
Collegeof Medicine)
OR years we have been led to believe that the unavoidable hemorrhage assoF ciated with placenta previa was on a purely mechanical basis. This theory, formulated by our predecessors, however, does not meet the test of time in many cases. Bleeding frequently occurs during the second and early stages of the third trimester of pregnancy, before these various mechanical factors can etlter the picture. In these patients, particularly, other predisposing etiological factors must be sought for and recognized. As is well known, placentation normally takes place well up on the uterine wall and far distant from the internal OS of the cervix. The de&dual reaction in this area is far better developed than in the lower uterine cavity, as is the local blood supply, and thus invites implantation of the embryo. Many conditions may occur, however, which will prevent normal placentation. Defective vascularization of the decidua as a result of inflammation or atrophic changes resulting from repeated pregnancies are among the more common causes. Neoplastic formations which encroach upon the uterine cavity and congenital malformations may prevent implantation in the upper portions of the uterus. Such atrophic changes naturally would limit the blood supply to the placenta. Therefore, the placenta must spread out its attachment and may thus border on, encroach upon, or cover over the internal cervical OS. Hofmeier’s theory, that of the development of the placenta in the decidua reflexa, must also be recognized as an etiological factor in placenta previa. During the latter weeks of pregnancy the lower uterine segment becomes thinned out, the cervix becomes effaced and dilated to some degree. As a result of this stretching the placenta is partially torn from its attachment with resulting hemorrhage. The mechanical process is undoubtedly the causative factor of bleeding in the great majority of eases, but by no means in all. Trauma may play an important role as an exciting factor in the production of bleeding in placenta previa. Unwarranted, repeated, or vigorous pelvic examination, either per rectum or vaginam, or coitus may produce hemorrhage of excessive degree. Such hemorrhage, however, is due to separation or penetration of the placenta and is also on a mechanical basis. Any or all unnecessary pelvic manipulations, especially in the fa,ce of abnormal bleeding, should be avoided. *Read Gynecologists
at
the Sixty-first Annual and Abdominal Surgeons.
Meeting of the American Hot Springs, Va., Sept.
855
Association of Obstetricians. 7. 8. and 9, 1950.
Of these, 10, UI’ nearly one-t,hird ul the cases, showed definite evidence of hypertensive toxemia associated with albuminuria. Although the records were incomplet,e. the majority (of the placentas examined showed extensiw areas of infarction, thus further evidence of toxemia. The placental pathology observed a,ppearetl identical to tha.t ionncl so frequently in abruptio placentae. It would seem logical to assume thrrci’ot*e that the bleeding in many eases of placenta previa, especially,those seen before the thirty-sixth week of gestation, is due to a tlisturhancc of placental circulation with resulting necrosis of the clecidua basalis and separation from the site of implantation.
Volume 61 Number 4
ETIOLOGY
OF
HEMORRHAGE
IN
PL,4CENTA
PREVIA
x57
During the same five-year period abruptio placent’ae was diagnosed 20 times or an incidence of 1 to 346 deliveries. Five of these cases, or 20 per cent, were terminated before the thirty-sixth week of gestation, the remaining 15 from the thirty-sixth week to term. There were 9 fetal deaths, an incidence of 45 per cent. Three of these fatalities occurred before the twenty-eighth week of pregnancy. This leaves a corrected fetal mortality rate of 30 per Ten patients were delivered by cent. There were no maternal deaths. cesarean section with 4 fetal deaths and 10 through the vaginal canal with 5 deaths. Six were primigravidas and 14 multigraridas. Eight, or 40 per cent, showed definite evidence of hypertensive toxemia. Although these two series of cases are extremely small, T feel that they are representative of these pathological conditions and that certain concluToxemia, of the hypertensive sions may be drawn from the above analysis. type, was noted in a large percentage of cases both in placenta previa and in abruptio placentae. The majority of patients were multigravidas. Placental pathology proved identical in both conditions in the majority of tissues examined. Trauma played a negligible inciting role in hoth. The fetal mortality rate was high in both series, there were no maternal deaths in either. The method of delivery varied with the individual patient’s condition and physical iindings. Tn review of the above discussion certain eases of placenta previa, as well as abruptio placentae, might be avoided by early recognition ‘and correct,ion of congenital abnormalities, the removal of neoplasms, the prevention of puerperal infection, and the proper spacing of children. Strict supervision of the pregnant patient, especially those with hypertensive toxemia and allied symptomzitology, might help to annul early hemorrhages and more pregnancies will be carried closer to term with a lessened fetal mortality rate. Summary The generally accepted theory that hemorrhage in placenta previa results purely from mechanical separation of the placenta following the development and formation of the lower uterine segment, effacement or dilation of the cervix, or following intravaginal manipulation must he disregarded. This is evident because many a patient presents symptoms during the seventh or eighth month of pregnancy before these mechanical factors become apparent. Many other factors must, be considered. Faulty implantation of the placenta, endometritis, or neoplastic formation must be included as possible etiological Careful prenatal supervision factors in the production of uterine hemorrhage. will help to reduce the incidence of pre-eclampsia and may thus help to carry more patients closer to maturity before the una.voitlable bleeding of placent;l previa, occurs. 446 AQUILA
COURT
Discussion DR. ment and intravaginal of placenta may serve As to lieve that
El. D. COLVIN, ATLANTA, GA.-I cannot formation of the lower uterine segment, manipulation must be disregarded ’’ previa. I do believe that any one or as an inciting cause in the production of the exact origin of bleeding in placenta modern obstetric writers have failed to
agree with Dr. Findley that ((the developeffacement or dilation of the cervix, or as etiological factors in the hemorrhage combination of the aforementioned factors such a hemorrhage. previa hemorrhage, I very strongly beplace the proper emphasis on an anatomic
structure which poysiMy is the origin of hemorrhage in many cases of placenta prrvia, thrmarginal sinus of the placenta. Jacquemier in 1839, J. Mathews Duncan in 1875, and Rudir in 1896 included rupture of the marginal sinus as one of the sources of bleeding in platzrnt:b previa and recognized that rupture of the sinus also occurs when the placenta is normall? situated. Practically every obstetrician of experience, in performing cesdrean section for plac*ent:t previa, has experienced the embarrassment of having found the placenta, not in the lo~r segment. but attached high in the uterus. Upon the removal of the placenta, its gross appear ante with attached blood clot at t.he edge rxtt~nding over the maternal surface of th*l adjacent cotyledons and the membranes is almost identienl to the picture foungl in placenta previa. Through close examination of all placentas we have come to the realizal.ion that rupture of the placental blood channel known as the marginal sinus is responsible for many hemorrhages erroneously diagnosed as due to placenta previa, abruptio placentae, or causes unknown. The marginal sinus is situated at the edge or just within the periphery of the marginal cotyledons, beneath the closing ring of Waldeyer, and is often involved in the fibrous chorionic It. is intermediary between the periphery and decidual degenerative concentrations at this site. of the suhchorionic maternal blood space and the uterine sinuses of the belt zone of the decidua basalis, into both of which many communicating openings are demonstrable on its medial and inferior walls. Variations in caliber a,nd thickness of the walls of the sinus are probably dependent on its involvement and the location of the marginal closing of the placenta. The excellent dissections of Rudolph Spanner of in situ placental specimens indicate that the marginal sinus bears fundamental importance to the circulation of the intervillous space of the placenta. It is conceivable that formation of the lower uterine segment late in pregnancy may so disturb the low placenta that rupture of the marginal sinus as well as or instead of separation of a cotyledon, may occur, with the result that blood spreads out over the membranes, separates the maternal surface of adjacent cotyledons, escapes through the cervix, and forms a clot locally adherent at the site of rupture on the placental margin. So often, examination of the area involved by the clot alone fails to enable one to differentiate between bleeding due to placenta previa and that of rupture of the marginal sinus or abruptio placentae. In the latter, it is our belief that the high incidence of clinical evidence of toxemia along with uterine findings and the ability to demonstrate acute infarction in the formalin-fixed placenta enables one to establish a diagnosis of abruptio placentae. From a rlinical viewpoint, it is important to keep in mind that extensive hemorrhage in the last trimester of pregnancy may be due to conditions other than placenta previa. Unfort,unately, diagnosis is not always possible. lf vaginal confirmation is omitted in selecting cases for expectant treat,ment, when placenta previa is suspected, consideration must be given in regard to bleeding due to true previa and ruptured marginal sinus in cases of normal There obviousiy implantat,ion of the placenta on the one hand, anti ahruptio on t,he other. c,xists no expectant treatment for abruptio placentae since this condition terminates pregnanay. ln an unpublished study, by Dr. John S. I+&, of 2,655 graridas tleliverecl consecutively Ivy the Bartholomew Group, there were found 117 eases of third trimester hemorrhage, oi hemorrhage in labor uf sueh an amount as to be of concern to the attendant. Fift,y one, or 34.6 per c+ent (17 proved ), were attributed to placenta previa: 50, or 33.9 per l,ent, resulted from a rupture of the marginal sinus in normally implanted placentas, and 14, 01 9.6 per cenl, In regard to the clinical behavior of hemorrhage due to accompanied ahruptio placentae. placenta previa and rupture of the marginal sinus in normally situated placentas, Dr. Fish (1 j placenta previa showed a greater tendeney made certain deductions, some of which arc: to recurrence of bleeding, also a higher incidence of bleeding before labor t-i9 per cent) than rupture of the marginal sinus (30 per cent), (2) in antepartum hemorrhage, rupture of the marginal sinus was attended by gross hemorrhage in ‘73.3 per cent, placenta previa in 56 per cent, (3) ruptured sinus bleeding was more often associated with labor (68 per cent),
gpm;r”b
ETIOLOGY
OF
HEMORRHAGE
IN
PLACENTA
PREVIA
859
apparently due to the irritation of retained blood and clots higher in the uterine cavity, (4) the bIood of ruptured sinus and placenta previa was bright red, but in abruptio it was more often a dark color, (5) evidences of toxemia were associated with abruptio placentae in 64.3 per cent, with ruptured marginal sinus in 8 per cent, and with placenta previa in 1.9 per cent, (6) the fetal mortality in placenta previa was 9.8 per cent, in abruptio placentae 28.6 per cent, and in ruptured marginal sinus 4 per cent. At the present time, it is my belief that, in all probability, the high degree of success attributed to the expectant plan of treatment of placenta previa, in the absence of vaginal examination, truthfully, but unknown, is the result of inclusion of a high percentage of hemorrhage cases labeled as placenta previa but due to blood loss from a rupture of the marginal sinus in normally implanted placentas.
OF HEMORRHAGE DAVID
(From the Departmentof
FINDLEY, Obstetrics
IN PLACENTA
M.D., and
OMAHA,
Gynecology,
PREVIA*
NEB.
University of Nebraska,
Collegeof Medicine)
OR years we have been led to believe that the unavoidable hemorrhage assoF ciated with placenta previa was on a purely mechanical basis. This theory, formulated by our predecessors, however, does not meet the test of time in many cases. Bleeding frequently occurs during the second and early stages of the third trimester of pregnancy, before these various mechanical factors can etlter the picture. In these patients, particularly, other predisposing etiological factors must be sought for and recognized. As is well known, placentation normally takes place well up on the uterine wall and far distant from the internal OS of the cervix. The de&dual reaction in this area is far better developed than in the lower uterine cavity, as is the local blood supply, and thus invites implantation of the embryo. Many conditions may occur, however, which will prevent normal placentation. Defective vascularization of the decidua as a result of inflammation or atrophic changes resulting from repeated pregnancies are among the more common causes. Neoplastic formations which encroach upon the uterine cavity and congenital malformations may prevent implantation in the upper portions of the uterus. Such atrophic changes naturally would limit the blood supply to the placenta. Therefore, the placenta must spread out its attachment and may thus border on, encroach upon, or cover over the internal cervical OS. Hofmeier’s theory, that of the development of the placenta in the decidua reflexa, must also be recognized as an etiological factor in placenta previa. During the latter weeks of pregnancy the lower uterine segment becomes thinned out, the cervix becomes effaced and dilated to some degree. As a result of this stretching the placenta is partially torn from its attachment with resulting hemorrhage. The mechanical process is undoubtedly the causative factor of bleeding in the great majority of eases, but by no means in all. Trauma may play an important role as an exciting factor in the production of bleeding in placenta previa. Unwarranted, repeated, or vigorous pelvic examination, either per rectum or vaginam, or coitus may produce hemorrhage of excessive degree. Such hemorrhage, however, is due to separation or penetration of the placenta and is also on a mechanical basis. Any or all unnecessary pelvic manipulations, especially in the fa,ce of abnormal bleeding, should be avoided. *Read Gynecologists
at
the Sixty-first Annual and Abdominal Surgeons.
Meeting of the American Hot Springs, Va., Sept.
855
Association of Obstetricians. 7. 8. and 9, 1950.
Of these, 10, UI’ nearly one-t,hird ul the cases, showed definite evidence of hypertensive toxemia associated with albuminuria. Although the records were incomplet,e. the majority (of the placentas examined showed extensiw areas of infarction, thus further evidence of toxemia. The placental pathology observed a,ppearetl identical to tha.t ionncl so frequently in abruptio placentae. It would seem logical to assume thrrci’ot*e that the bleeding in many eases of placenta previa, especially,those seen before the thirty-sixth week of gestation, is due to a tlisturhancc of placental circulation with resulting necrosis of the clecidua basalis and separation from the site of implantation.
Volume 61 Number 4
ETIOLOGY
OF
HEMORRHAGE
IN
PL,4CENTA
PREVIA
x57
During the same five-year period abruptio placent’ae was diagnosed 20 times or an incidence of 1 to 346 deliveries. Five of these cases, or 20 per cent, were terminated before the thirty-sixth week of gestation, the remaining 15 from the thirty-sixth week to term. There were 9 fetal deaths, an incidence of 45 per cent. Three of these fatalities occurred before the twenty-eighth week of pregnancy. This leaves a corrected fetal mortality rate of 30 per Ten patients were delivered by cent. There were no maternal deaths. cesarean section with 4 fetal deaths and 10 through the vaginal canal with 5 deaths. Six were primigravidas and 14 multigraridas. Eight, or 40 per cent, showed definite evidence of hypertensive toxemia. Although these two series of cases are extremely small, T feel that they are representative of these pathological conditions and that certain concluToxemia, of the hypertensive sions may be drawn from the above analysis. type, was noted in a large percentage of cases both in placenta previa and in abruptio placentae. The majority of patients were multigravidas. Placental pathology proved identical in both conditions in the majority of tissues examined. Trauma played a negligible inciting role in hoth. The fetal mortality rate was high in both series, there were no maternal deaths in either. The method of delivery varied with the individual patient’s condition and physical iindings. Tn review of the above discussion certain eases of placenta previa, as well as abruptio placentae, might be avoided by early recognition ‘and correct,ion of congenital abnormalities, the removal of neoplasms, the prevention of puerperal infection, and the proper spacing of children. Strict supervision of the pregnant patient, especially those with hypertensive toxemia and allied symptomzitology, might help to annul early hemorrhages and more pregnancies will be carried closer to term with a lessened fetal mortality rate. Summary The generally accepted theory that hemorrhage in placenta previa results purely from mechanical separation of the placenta following the development and formation of the lower uterine segment, effacement or dilation of the cervix, or following intravaginal manipulation must he disregarded. This is evident because many a patient presents symptoms during the seventh or eighth month of pregnancy before these mechanical factors become apparent. Many other factors must, be considered. Faulty implantation of the placenta, endometritis, or neoplastic formation must be included as possible etiological Careful prenatal supervision factors in the production of uterine hemorrhage. will help to reduce the incidence of pre-eclampsia and may thus help to carry more patients closer to maturity before the una.voitlable bleeding of placent;l previa, occurs. 446 AQUILA
COURT
Discussion DR. ment and intravaginal of placenta may serve As to lieve that
El. D. COLVIN, ATLANTA, GA.-I cannot formation of the lower uterine segment, manipulation must be disregarded ’’ previa. I do believe that any one or as an inciting cause in the production of the exact origin of bleeding in placenta modern obstetric writers have failed to
agree with Dr. Findley that ((the developeffacement or dilation of the cervix, or as etiological factors in the hemorrhage combination of the aforementioned factors such a hemorrhage. previa hemorrhage, I very strongly beplace the proper emphasis on an anatomic
structure which poysiMy is the origin of hemorrhage in many cases of placenta prrvia, thrmarginal sinus of the placenta. Jacquemier in 1839, J. Mathews Duncan in 1875, and Rudir in 1896 included rupture of the marginal sinus as one of the sources of bleeding in platzrnt:b previa and recognized that rupture of the sinus also occurs when the placenta is normall? situated. Practically every obstetrician of experience, in performing cesdrean section for plac*ent:t previa, has experienced the embarrassment of having found the placenta, not in the lo~r segment. but attached high in the uterus. Upon the removal of the placenta, its gross appear ante with attached blood clot at t.he edge rxtt~nding over the maternal surface of th*l adjacent cotyledons and the membranes is almost identienl to the picture foungl in placenta previa. Through close examination of all placentas we have come to the realizal.ion that rupture of the placental blood channel known as the marginal sinus is responsible for many hemorrhages erroneously diagnosed as due to placenta previa, abruptio placentae, or causes unknown. The marginal sinus is situated at the edge or just within the periphery of the marginal cotyledons, beneath the closing ring of Waldeyer, and is often involved in the fibrous chorionic It. is intermediary between the periphery and decidual degenerative concentrations at this site. of the suhchorionic maternal blood space and the uterine sinuses of the belt zone of the decidua basalis, into both of which many communicating openings are demonstrable on its medial and inferior walls. Variations in caliber a,nd thickness of the walls of the sinus are probably dependent on its involvement and the location of the marginal closing of the placenta. The excellent dissections of Rudolph Spanner of in situ placental specimens indicate that the marginal sinus bears fundamental importance to the circulation of the intervillous space of the placenta. It is conceivable that formation of the lower uterine segment late in pregnancy may so disturb the low placenta that rupture of the marginal sinus as well as or instead of separation of a cotyledon, may occur, with the result that blood spreads out over the membranes, separates the maternal surface of adjacent cotyledons, escapes through the cervix, and forms a clot locally adherent at the site of rupture on the placental margin. So often, examination of the area involved by the clot alone fails to enable one to differentiate between bleeding due to placenta previa and that of rupture of the marginal sinus or abruptio placentae. In the latter, it is our belief that the high incidence of clinical evidence of toxemia along with uterine findings and the ability to demonstrate acute infarction in the formalin-fixed placenta enables one to establish a diagnosis of abruptio placentae. From a rlinical viewpoint, it is important to keep in mind that extensive hemorrhage in the last trimester of pregnancy may be due to conditions other than placenta previa. Unfort,unately, diagnosis is not always possible. lf vaginal confirmation is omitted in selecting cases for expectant treat,ment, when placenta previa is suspected, consideration must be given in regard to bleeding due to true previa and ruptured marginal sinus in cases of normal There obviousiy implantat,ion of the placenta on the one hand, anti ahruptio on t,he other. c,xists no expectant treatment for abruptio placentae since this condition terminates pregnanay. ln an unpublished study, by Dr. John S. I+&, of 2,655 graridas tleliverecl consecutively Ivy the Bartholomew Group, there were found 117 eases of third trimester hemorrhage, oi hemorrhage in labor uf sueh an amount as to be of concern to the attendant. Fift,y one, or 34.6 per c+ent (17 proved ), were attributed to placenta previa: 50, or 33.9 per l,ent, resulted from a rupture of the marginal sinus in normally implanted placentas, and 14, 01 9.6 per cenl, In regard to the clinical behavior of hemorrhage due to accompanied ahruptio placentae. placenta previa and rupture of the marginal sinus in normally situated placentas, Dr. Fish (1 j placenta previa showed a greater tendeney made certain deductions, some of which arc: to recurrence of bleeding, also a higher incidence of bleeding before labor t-i9 per cent) than rupture of the marginal sinus (30 per cent), (2) in antepartum hemorrhage, rupture of the marginal sinus was attended by gross hemorrhage in ‘73.3 per cent, placenta previa in 56 per cent, (3) ruptured sinus bleeding was more often associated with labor (68 per cent),
gpm;r”b
ETIOLOGY
OF
HEMORRHAGE
IN
PLACENTA
PREVIA
859
apparently due to the irritation of retained blood and clots higher in the uterine cavity, (4) the bIood of ruptured sinus and placenta previa was bright red, but in abruptio it was more often a dark color, (5) evidences of toxemia were associated with abruptio placentae in 64.3 per cent, with ruptured marginal sinus in 8 per cent, and with placenta previa in 1.9 per cent, (6) the fetal mortality in placenta previa was 9.8 per cent, in abruptio placentae 28.6 per cent, and in ruptured marginal sinus 4 per cent. At the present time, it is my belief that, in all probability, the high degree of success attributed to the expectant plan of treatment of placenta previa, in the absence of vaginal examination, truthfully, but unknown, is the result of inclusion of a high percentage of hemorrhage cases labeled as placenta previa but due to blood loss from a rupture of the marginal sinus in normally implanted placentas.