Keywords : conjoint twins, dicephalic twin, dicephalic monster
An interesting anomaly unique to multiple pregnancies is conjoint twins. This is a rare disorder affecting 1:200 monozygotic twin pregnancies, 1:900 twin pregnancies and 1:25,000 to 100,000 births.
Conjoint twins develop when incomplete separation occurs
after the development of the embryonic plate at 8 days.
Depending upon the site of fusion or nonseparation the types
of the twins may differ. Common varieties are the
thoracopagus (40%), omphalopagus (35%), cephalopagus
(2%), pyopagus (18%), and ischiopagus (2%) 1
. The
management of such twins if diagnosed early is termination
of the pregnancy. If diagnosed late at term or during labor
delivery by cesarean section is usually undertaken.
A 18 year old primigravida, resident of a village nearly 100 km away from our center, came with a history of 9 months amenorrhea, labor pains since one day, and leaking since 10 hours. A local dai (untrained midwife) had failed to deliver her.
At the time of admission her general condition was fair, pulse 120 / minute, and blood pressure 110/70mm Hg. She looked pale and had no edema. Systemic examination revealed no abnormality.
Obstetric examination revealed her to be in obstructed labor, with intrauterine fetal death. She delivered a hydrocephalic head spontaneously within few minutes of admission. There was no further progress of labor. Considering shoulder dystocia as the possible cause, one of the hands was delivered, which had two palms. Again further delivery of the fetus could not be achieved. She was shifted to the operation theater. Under general anesthesia, on giving traction to the delivered head and the hand the shoulder got disimpacted and it was revealed that there was another neck going towards the left of the head already delivered. By manipulation, the second head was delivered and the rest of the body was now easily delivered.
It was a 4 kg macerated male baby with peeling of the skin. The neck of the left sided head of the baby was slightly lacerated during traction. In addition, the left arm showed fracture of the humerus (Figure 1) . The male baby had single well formed external genitalia. There was a normally situated anus and a small dimple above it.
She had mild postpartum hemorrhage and though there was no extension of the episiotomy wound the vagina was lacerated. Episiotomy and the lacerations were repaired. Her postnatal period was uneventful.
Postdelivery x-ray of the fetus (Figure 2) showed that –
1. There were two vertebral columns separate till the sacrum. The pelvis was single.
2. One of the head was hydrocephalic, the other was normal.
3. There were three upper limbs, the central one was fused. The fused arm showed two humerii, two radii two ulnae and two separate palms.
4. There were two lower limbs but one fused thorax and abdomen.
CT scan and ultrasonographic examination revealed that the baby had two separate thoracic cavities in its upper part but the lower part was fused. There were four kidneys. Retrograde filling of the bladder revealed only a single bladder. The left sided kidneys were pelvic in situation.
The mother had an uneventful postnatal recovery. She was
discharged on the 7th day.
Dicephalic fused twin or double-headed monster is a variety of conjoint twin with fused thorax and abdomen. The incidence is 1:50,000 to 1:100,000. It is rare for such type of twins to survive. The classic examples being Scottish brothers who attained 28 years age, Rita-Christina born in Sardina in 1829 and Tocci brothers born in Italy in 1877 2 .
Goel and Goel 3 , also reported a twin delivered by cesarean section having two heads, two arms, a single body and two lower limbs.
The present conjoint twin was a rare case in many ways.It
had two heads and two necks but one of the heads was
hydrocephalic and the other was normal. The fused arm had
fusion up to the forearm with separation of the palms. It had
two separate vertebral columns until the end and a single
pelvis. It also had four kidneys but one bladder. The kidneys
of the smaller baby were pelvic. She was a primigravida and
delivered vaginally successfully. She had adequate pelvis. At
admission there were no fetal heart sounds and the baby was
partially delivered. These facts helped vaginal delivery.
