Address correspondence to Winston A. Campbell, MD, Department of Obstetrics & Gynecology, Division, Maternal-Fetal Medicine, University of Connecticut Health Center, 263 Farmington avenue, Farmington, CT 06030-1230; Ph: 203-679-4363; Fax: 203-679-1271

Synonyms: Abruptio placentae, placental abruption, premature separation of the normally implanted placenta.

Prevalence: Range 49-129:10,000, median rate of 83:10,000 (1 in 120 deliveries). An incidence of 20:10,000 (1 in 500) if the abruption is severe enough to kill the fetus.

Definition: Separation (partial or complete) of a normally implanted placenta from the uterus, before the birth of the fetus.

Etiology: Primary cause is uncertain. Many associated clinical risk factors have been described. They are: 1) hypertensive disorders, 2) cigarette smoking, 3) abdominal trauma, 4) grand multiparity, 5) cocaine abuse, 6) prior history of abruption.

Differential diagnosis: Varies with presentation: 1) abdominal pain with bleeding - placenta previa, uterine rupture, 2) abdominal pain without bleeding labor, chorioamnionitis, appendicitis, pyelonephritis.

Prognosis: Varies with severity of abruption and gestational age at presentation. Reported perinatal mortality has ranged between 20-35%. Maternal morbidity and mortality may be increased in severe cases or when disseminated intravascular coagulation develops.

Recurrence risk: Reported to range between 5.5-16.6%. If severe (causes fetal death) recurrence after one episode is 7%; this rises to 25% after two severe episodes.

Management: When the pregnancy is at term, the best outcome is obtained by delivering the patient. In preterm gestations delivery should be undertaken if there is evidence of maternal or fetal compromise. Conservative management can be used if the abruption is not progressive, there is no maternal or fetal compromise, and close observation and monitoring can be maintained.

MESH Abruptio placentae, Twins ICD9 641.2 CDC 641.200

Introduction

Vaginal bleeding during pregnancy is suggestive of a spontaneous miscarriage (threatened or incomplete), placenta previa or placental abruption. Ultrasonography has become very useful in the evaluation and management of this obstetrical problem. Its benefit has been to document whether the source of bleeding is from a placenta previa. In the absence of a placenta previa, the diagnosis of placental abruption by ultrasound may not be sensitive enough unless a retroplacental hematoma can be identified. We report a case of placental abruption in a twin pregnancy with an unusual location of the hematoma identified on ultrasound examination.

Case report

A 41-year-old G₄P_2-0-1-2 white female with a known twin gestation at 26 weeks, 5 days was referred to our institution for vaginal bleeding. Placental abruption was suspected. Her prenatal history was significant for conception after ovulation induction, and documentation of a twin pregnancy by ultrasound at 7 and 14 weeks gestation. The ultrasounds were performed because of vaginal bleeding. These ultrasounds documented two anterior placentas without evidence of previa or abruption. She underwent an exploratory laparotomy and right salpingoophrectomy for adnexal torsion, at 10 weeks gestational age. She did not have a history of hypertension, drug use, smoking or acute abdominal trauma. Evaluation after admission demonstrated a normal general physical examination. Her blood pressure was 120/70 mm Hg, pulse 120 bpm, temperature 37.7º. With continued observation at bed rest, her pulse gradually decreased to 90 bpm, her temperature to 36.6º, and blood pressure to 100-1 14/ 68-70 mm Hg. There was no evidence of uterine activity or active vaginal bleeding. An ultrasound examination confirmed the twin gestation and growth measurements of twin A (female) and twin B (male) were consistent with the menstrual dates. The biophysical profiles were: A: 12/12 and B: 10/12¹.

Two anterior placentas were identified and separating membranes visualized. A homogeneous echogenic mass measuring 80 x 40 mm (widest segment) was noted within the amniotic cavity (fig 1).

  Figure 1: Longitudinal and transverse scan of the hematoma on admission, demonstrating the seperation of the two amniotic sacs (a=sac A, b=sac B).

Further evaluation of this mass indicated that it was separate from the placentas and was continuous with the membranes separating the fetuses. It was felt that this mass represented blood that had dissected between the chorionic membranes.

Speculum examination revealed a small amount of blood in the vaginal vault. There was no active bleeding from the cervix, and the cervix appeared closed. The patients blood type was B positive, a Kleihauer-Betke stain was negative, Hb 10.1 g/dl, Hct, 30.2%, platelet count 173,000, Pt 11.7 seconds (normal 10-14), PTT 22.8 seconds (normal 24-36), fibrinogen 349 mg/dl. Since there was no evidence of maternal or fetal compromise the patient received two doses of Celestone and remained in the hospital for continued observation. Her vital signs and hematologic status remained stable on serial evaluation.

Over the next ten days the patient had subsequent episodes of vaginal bleeding. These were limited to dark red spotting, did not occur on a regular basis, and were not associated with pain. She had two episodes of passing small well organized clots. On the fourth hospital day an episode of uterine contractions responded to intravenous hydration.

A repeat evaluation of the hematoma indicated that it had not increased in size (77 x 49 mm) from admission (fig 2).

  Figure 2: Transverse view of the hematoma at its widest segment measuring 80 x 40 mm. The open arrow demarks area of apposition of the two placentas, The closed arrow points out where the membranes originate from the placentas.

Twice a week antepartum fetal evaluation remained reassuring. In the evening of the 11^th hospital day (28w-2d) she complained of continuous painless vaginal bleeding. Uterine activity monitoring revealed irregular contractions. She was transferred to the Maternal- Fetal Intensive Care Unit for further evaluation and observation. Ultrasound evaluation revealed that the hematoma had increased in size to 87 x 48 mm (at its widest segment). After five hours of observation, the bleeding decreased to minimal spotting, but the uterine contractions had become more regular (every 3 minutes), and the patient was now aware of the contractions. The fetal heart rate tracings were stable and reactive. The patient was started on Magnesium Sulfate for tocolysis. The bleeding stopped. However, despite tocolysis she continued to contract; and the contractions were more uncomfortable.

A repeat ultrasound revealed a further increase in the hematoma to 114 x 57 cm (fig 3).

  Figure 3: Repeat evaluation of the hematoma in a transverse plane on hospital day 4. Caliper measurements: 77 mm, and 49 mm.

In addition to the increased size, the hematoma now had a heterogeneous appearance to, it. There was a echolucent distal layer, and a proximal echogenic layer. It was felt that the abruption was progressing, the patient was becoming more symptomatic, and the fetal heart rate tracings were now non-reactive.

She was delivered by repeat cesarean section under general anesthesia. Twin A (female) weighed 1137g; cord arterial pH 7.3, PCO₂ 42.1 mm Hg, P0₂ 31.5 mm Hg, Base Excess - 3.1 mmol/l. Twin B (male) weighed 1185g; cord arterial pH 7.32, PCO₂ 50.0 mm Hg, P0₂ 21.8 mm Hg, Base excess -8.4.mmol/l. After removal of the first placenta, there was a large amount of blood and clot (450g) covering the membranes of the remaining placenta (fig 4). This blood and clot was felt to be the hematoma that was seen on ultrasound examination.

  Figure 4: Ultrasound examination on day of delivery. The size of the hematoma had increased and the echo pattern was heterogenous. The arrows outline the sonolucent area below the echo dense area of the hematoma (H).

The mother had an uncomplicated post operative course except for anemia (Hb 9.5, Hct 28.2). She was not symptomatic. She did not require blood transfusion and was started on oral hematinics. The infants did well and were discharged alive on hospital day 77 (twin A), and 91 (twin B). Pathologic examination of the placenta of Twin A was not remarkable. However, the examination of the Twin B placenta showed marginal subchorionic hemorrhage with organization (fig. 5).

Discussion

Diagnostic criterias

The diagnostic criteria of placental abruption includes the presence of a retroplacental hemorrhage, (diagnosed if a well demarcated anechoic area is seen), and a bulging of the chorionic plate (if the hematoma is large enough) ².

It is well documented in the literature that there is a variable appearance to the ultrasound findings of placental abruption^3-7; and that the sensitivity of diagnosis by ultrasound varies (2-20%)⁷.

Localization

If the blood has become organized by the time of the ultrasound examination, its location can be subchorionic (81%), retroplacental (16%) or preplacental (4%) ⁷. Differences in location can also be seen depending upon the gestational age at the time of diagnosis. The incidence of subchorionic hematomas is less after 20 weeks gestation (91% in gestations less than 20 weeks versus 67% in gestations greater than 20 weeks). The frequency of retroplacental hematomas increases after 20 weeks (6% in gestations less than 20 weeks vs 29% in gestations greater than 20 weeks) ⁷.

Appearance

The acuteness of the hemorrhage will also influence its appearance. Acute hemorrhages have a hyperechoic to isoechoic appearance (compared to the placenta); within a week they become hypoechoic and then sonolucent within two weeks of their formation^6,7. In the absence of a recognizable hematoma other features of an abruption are, a thickening of the placenta^4-6, retroplacental or intraplacental sonolucent areas^4,5, and abnormal shape of the placental edge (round, irregular or edge separation)⁴.

In the clinical setting of suspected abruption a placental thickness of greater than 50 mm is indicative of abruption (in the absence of other causes abruption of increased placental thickness eg. hydrops, diabetes, congenital syphilis). This thickened appearance might reflect the acute nature of the bleed at which time the blood can be isoechoic to the placenta and thus give this thickened appearance. The other unusual finding that we noted was the heterogenic echo pattern of the hematoma as the bleeding acutely resumed prior to delivery. This was due to the mixed nature of the hematoma at this time, the presence of an older well formed hematoma with additional fresh hematoma formation in the same interchorionic space.

Differential diagnosis

The sonolucent areas probably represent an older resolving hematoma. Sonolucencies seen in a retroplacental location, should be interpreted with caution. There are normal retroplacental sonolucent areas seen after 12 weeks gestation that are felt to represent the dilated vessels of the decidua basalis⁸. These normal sonolucent areas range from 5-20 mm in thickness. In cases of fundal placentas they are smooth with feathered margins and with posterior placentas they appear multiseptate.

Summary

There have been reports of unusual ultrasound findings associated with placental abruption. The presence of blood in the fetal stomach⁹ , massive intra-amniotic bleeding⁵, and intra-amniotic hematomas^10,11 have been considered unusual findings. Our case is also unusual in that the hematoma was inter-chorionic (between the dividing membranes) in a twin gestation. The location of the hematoma was in the potential space between the chorionic membranes of these dizygotic fetuses. Although there was external manifestations of the abruption, it was not in proportion to the amount of blood that was being sequestered in the inter-amniotic site. Bleeding into this area has the potential to sequester a significant amount of blood. Its increase in size could be indicative of the deterioration of what might seem to be an otherwise stable clinical situation.

As with all cases of abruption, a conservative approach to clinical management will be influenced by factors such as severity of the abruption, gestational age and the maternal and/or fetal status. Hill et al. has suggested that mild abruptions (grade 1) (Table 1) should be further subcategorized based on the presence or absence of a ultrasonically detectable hemorrhage¹¹, and that this information might be useful in the management of placental abruption. We are not aware of any large series of cases that utilizes this suggestion, therefore management based upon such findings will still differ among clinicians. If the type of abruption presentation that we have described is found in a multifetal gestation, it seems prudent to serially evaluate the size and appearance of the hematoma. An increase in the size of the hematoma or change in its ultrasound appearance (heterogenic echo pattern) could signify progression of the abruption and necessitate a change in a conservative management approach.

Table 1: Classification of placental abruption¹²

Grade	Concealed hemorrhage	DIC	Shock	Fetal distress	Uterine tenderness	Other findings
0	No	No	No	No	No	Retrospective diagnosis by placenta review. No clinical symptoms
1	No	No	No	No	No	Variable blood loss. Includes the diagnosis of marginal sinus separation.
2	Yes	Rare	No	Yes	Yes	Progression to higher grade if not delivered.
3	Yes, extensive	Yes, common	Yes	Yes, death	Yes	Maternal morbidity.

DIC = Disseminated intravascular coagulation

References

1. Vintzileos AM, Campbell WA, Ingardia CJ, et al.: The fetal biophysical profile and its predictive value. Obstet Gynecol 62:271- 278, 1983.

2. Kobayashi M.: Placental Scan, placenta previa and abruptio placentas. In: Kobayashi M, ed. Illustrated manual of ultra-sonography in obstetrics and gynecology. Philadelphia: Lippincott, 252-254, 1974. 3. Spirt BA, Kagan EH, Rozanski RM.: Abruptio placenta: Sonographic and pathologic correlation. AJR 133:877-881, 1979.

4. Jaffe MH, Schoen WC, Silver TM, et al.: Sonography of abruptio placentas. AJR 137:1049-1054, 1981.

5. McGahan JP, Philips HE, Reid MH, et al.: Sonographic spectrum of retroplacental hemorrhage. Radiology 142:481-485, 1982.

6. Mintz MC, Kurtz AB, Arenson R, et al.: Abruptio placentae: Apparent thickening of the placenta caused by hyperechoic retroplacental clot. J Ultrasound Med 5:411-413, 1986.

7. Nyberg DA, Cyr DR, Mack LA, et al.: Sonographic spectrum of placental abruption. AJR 148: 161-164, 1987.

8. McGahan JP, Philips HE, Reid MH.: The anechoic retroplacental area. A pitfall in the diagnosis of placental-endometrial abnormalities during pregnancy. Radiology 134:475-478, 1980.

9. Walker JM, Ferguson DD.: The sonographic appearance of blood in the fetal stomach and its association with placental abruption. J Ultrasound Med 7:155-161, 1988.

10. Hill LM, Breckle R, Gehrking W.: Abruptio placentas: An unusual ultrasonic presentation. Am J Obstet Gynecol 148: 1144-5, 1884.

11. Hill LM, Breckle R.: Fetal outcome after intraamniotic hemorrhage with placental abruption. A report of three cases. J Reprod Med 31: 1065-70, 1986.

12. Page EW, King EB Merrill JA: Obstet Gynecol 3:385-93, 1954.