Shereen Z. Bhutta ( Department of Obstetrics and Gynaecology, Jinnah Postgraduate Medical Centre, Karachi. )
Gestational trophoblastic disease encompasses a wide spectrum of conditions with variable presentations. Twin pregnancy with a complete hydatidiform mole and a coexistent normal foetus is encountered rarely. Two such cases seen at the Department of Obstetrics and Gynaecology, Jinnah Postgraduate Medical Centre, Karachi, between Januazy, 1992 and July, 1995 are described.
A 25 year old pam 1+0 with a previous normal delivezy was seen at 18 weeks gestation with hyperemesis. There was no histoiy of vaginal bleeding. The uterus corresponded to 30 weeks size, otherwise examination was unremarkable. Ultrasound scan showed a twin pregnancy, an 18 weeks size normal live foetus with anterior placenta and a separate hydatidiform mole in the lower part of uterus near the posterior wall. Serum beta human chorionic gonadotmphin (hCG) was 618,850 mIU/ml. The patient then lost contact with the hospital till admitted in emergency at 26 weeks gestation with heavy vaginal bleeding. Suction evacuation of the uterus through a 2 cm dilated cervix was attempted unsuccessfully, followed by emergency lower segment Caesarean section to empty the uterus and arrest haemorrhage. An 800 grams live male foetus and normal fundal placenta were delivered after amniotomy. Molar tissue filling up 1100 ml volume without any connection with the other placenta was removed separately from the lower portion of the uterus. Bilateral orange size theca lutein cysts were observed in the ovaries. Six units of whole blood and 1000 ml ‘Haemaccel’ were transfused before and during the procedure. The baby died 30 minutes after delivery. Chest X-ray and postoperative period were normal. Autopsy of the foetus and placental histology revealed no abnormality and second conceptus was confirmed to be complete hydatidiform mole. B-hCG six weeks later was in the non-pregnant range. She has subsequently delivered a normal male baby and remains well.
A 27 year old pam 2+0 with previous normal deliveries was admitted in shock at 18 weeks pregnancy with heavy vaginal bleeding. The 30 weeks size uterus was contracting intennitently and molar tissue with blood clots was being expelled through the 5 cm dilated cervix. Molar tissue was evacuated with suction and sponge forceps. A separate anmiotic sac was ruptured and a 500 grams macerated male foetus and placenta were delivered (Figure 1).
Four units of whole blood and 1000 ml ‘Haemaccel’ were transfused altogether. Serum B-hCG on the following day was 350 mIU/ml and chest X-ray was normal. The histopathology report confirmed a normal male foetus and placenta. The vesicular tissue removed separately turned out to be complete hydatidiform mole (Figure 2).
Six weeks later, the patient was well and serum B-hCG was less than5 mIU/ml. The couple are using the sheath for contraception presently.
A pregnancy with a complete mole and a normal foetus is very rare, with a reported incidence vaiying between 0.005 and 0.01% of trophoblastic gestations1. The condition is believed to be more common after assisted reproduction techniques, consequent upon ovum handling causing genetic damage2. A twin pregnancy with a complete hydatidiform mole and a normal foetus as an accompanying conceptus is different from molar change in the placenta of a single foetus. In former foetal loss may occur in early pregnancy without leaving gross evidence of “a vanishing twin3, whereas in latter the foetus is usually aneuploid with poor prognosis2,4-6
Exaggerated signs and symptoms of pregnancy with a uterus larger than the period of gestation and abnormally high levels of hCG8,9 are an indication for an ultrasound examination. This would detect a twin pregnancy with hydatidiform mole and a coexistent foetus. Most such pregnancies underrgo spontaneous termination by end of second trimester10 with less than 20 such children zeported in world literature todate11.
The dilemma for the clinician arises in continuing pregnancy following diagnosis. While some authors recommend immediate tennination11,12, others hold a different view. Prenatal diagnosis with amniocentesis rather than chorion villous sampling (CVS) is preferable because with CVS, the area biopsied may not be representative of the entire placenta3, leading to erroneous results in partial moles. After confirmation of normal karyotype in the coexistent foetus and appropriate patient counselling, continuation of pregnancy can be attempted despite a 30% risk of bleeding and preeclampsia. Treatment of associated complications like thyrotoxicosis is recommended3.
Natural course of these pregnancies is unpredictable2, with 60% going beyond 28 weeks3. Length of pregnancy has no impact on complications like persistent trophoblastic disease3 or malignant sequelae. Favourable response to ch emotherapy in gestational trophoblastic disease is another factor favouring conservative approach12,13.
Confirmation of diagnosis at abortion or delivezy is essential. The karyotype of 95% complete moles is female (46,XX), so a coexisting male foetus adds weight to the diagnosis of twin conception rather than molar change in a singleton placenta14,15, however, external genitalia are not always representative of the actual sex10. It is, therefore,
recommended to perform histology and if available, tissue karyotype9 and even analysis of chromosome polymorphism14 for definitive diagnosis. Follow-up and prognosis of these women does not differfrom otherwomen with complete hydaticliform moles3.
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