76 mbryology ACARI}IA ACEPHALUS TWIN . A CASE REPORT Dr. Manala S., Dr. Dakshayani K.R. Dr. Dakshayani K.R. Professor and Head Department of Anatomy Mysore Medical College And Research Institute Mysore - 570 001 Mobile no - 9448739656 E-mail dakshay anikr@ gmail. c om Dr. Mangala S. Post graduate Department of Anatomy Mysore Medical Coltege And Research Institute Mysore - 570 001 Mobile no - 9986019997 E-mail - dr [email protected] : monochorionic, vascular anastomoses, ABSTRACT During routine fetal autopsies conducted in the department of Anatomy', a rate case of fullterm female Acardia Acephalus twin was observed, The autopsy findings revealed acardiac twin showing right sided diaphragmatic hernia, absence of brain, spinal cord, respiratory system, upper Iimb Amelia with rudiments of heart and urogenital system, partially developedcm and syndactyly of right i foot. ) reversed arterial perfusion INTRODUCTION Acardia is a rare and severe congenital malfoimation unique to mon ozygottc, monochorionic multiple gestation with vascular anastomoses which is hemodynamically srgmfrcant It iS thE TESUII Of TWIN REVERSAL ARTERIAL PERFUSION SEQUENCE Fetal acardia is a rare dysmorphic problem which is unique to monochorionic pregnancies occurs with an incidence of l:35000 deliveries with vascular anastomoses.'It is due to a sequence described as TRAP Twin Reversed Arterial Perfusion, with an incidence of I in SINGLEPLACENTA. This condition has a 35,000 births. The present case gains significance because and in l7o of monozygotic gestation with fernale preponderance. Out of 4 different types of Acardia twins, Acardia Acepahlus is the commonest. of its pattern of hemodynamically significant The present case report adds to the literature anastomotic circulations in monochorionic, monozygotic multiple gestation. for typical example of an acardiac acephalic KEY WORDS MATERIALS AND METHODS Acardia Acephalus, mono zY gotic, monster. A 22 year old second gravida with no 77 significant past history delivered twins with gestational bge of about 34 weeks at K.R. Hospital, Mysore attached to MMC&RI. The first twin was a female weighing 2 kgs and was Acephalic monster (present case). The second twin born after 5 minutes was a live normal female baby weighrng 1.5 kg. Mother has a Zyearold healthy male child from previous conception. Autopsy of the acardiafetus was done in the Department of Anatomy, MMC & R[, and x-ray of the same was taken in the department of Radiology, K.R. Hospital attached to MMC&RI. OBSERVATION AND RESULTS 1. Blunt and covered with sparse hair. 2. Absence of lungs with empty pleural sac. 3. Rudimentary tubular cardia. 4. Incomplete diaphragm 5. Normal ureters 6. with Right fallopian tube. CTEV deformity bilaterally. External features: In the present case, the fetus was covered with thick skin that was soft and oeddmatous. There was no distinct Head. Instead there was a blunt cranial end covered with sparse hair and some small cranial bony remnants. Upperlimbs were absent. Lowerlimbs were near normal except for BIL CTEV. Right foothad four digits with syndactyly of third and fourth digits. 1. Rudimentary cranial skeleton. 2.Yertebral column 3. Pelvic girdle bones 4. CTEV with Thrsal bones. Irft foot-had four digits. Anterior abdominal wal I -compl ete, external genitalia-normal, suggestive of female sex. , Anal orifice-patent. AUTOPSYFINDINGS 78 CRANIOTO-MY : revealed absence of brain and spinal cord. THORACOTOMY : absence of trachea and lungs rudimentary tubular cardia with arterial and venous ends. Incomplete SEQUENCE (TRAP sequence),'unique to monozygotic twinning. The etiology of acardia is either a primary heart defect in one twin or reversed arterial perftrsion from the pump tw'in to acardiac twin. (Craven C et al 1999). LAPAROTOMY : revealed oesophagus with proximal blind end with apafiof stomach It represents a variant of conjoined twins in which thejunction is the chorionic circulation. Normal twin is the 'pump twin'. Acardiac twin is the 'perfused or recipient twin'.,The'pump herniating i,nto right side o{thror:acic cavity. twin provides circulation forbothitself and the devel opment of diaphragm acardiac twin. Parts'of duodenum present Rudimrints of liver seen. Bilateral kidneys with ureters and urinary bladder seen. Rudiments of uterus with right fallopian trrbe and ovary present. Largeblood vessels of abdomen seen. Absence of coils of intestine, spleen and pancfeas. RADIOLOGICAL FINDINGS: Revealed a disproportionate massof soft tissue. Rudimentary cranial skeleton was seen. Vertebral column was present. Ribcage was with absence of upper limbs and pectoral girdle. Pelvic girdle present with lower limb seen bones. DISCUSSION EMBRYOLOGY: Acardiac twinning is the result of disruption in norganogenesis due to arterial-placental anastomosis in the early embryonic period. This is also called as TWIN REVERSED ARTERIAL PERFUSION The perfused twin has no direct vascular connectilon with placenta and the blood enters directly through a single umbilical artery and exits thtough the urnbilical vein. TRAP sequence is caused in the embryo by a sizable artery to artery placental shunt, often ,accompanied by vein to vein shunt. (Cunnigh*tr F9 et al 2005). The placental pressure of one twin overpowers the other who then has reverse blood flow from the co-twin. The ,'used' arterial blood reaching the recipient twin preferentially gogs to the iliac yessels and thus perfuse only the lower pan of the body, leading to disnrption ordeterioration of growth and development of the upperbody. Hypoxicflow via arterial communications from the 'pump' twin results in panial reabsorption of normal tissues of acardiac fetus. TYPES: According to Izquierdo L et al IggL Four different types of acardiac twins have been categonzed based on the degree cephalic and truncal maldevelopment. of 1. ACARDIA ACEPHALIC - where no cephalic structures are present. 79 2. ACARDIA ANCEPS - in which some cranial structures are present with or without secondary to prematurity. The combined circulation of purnp twin may result in neural tissue. cardiomegaly and congestive heart failure. 3. ACARDIA ACORMUS - in which cephalic structures are present with no truncal The progno.sis worsens when polyhydramnios, pre term labour or cardiac decompensation complicates the condition. Monozygotic twins have also been shown to have a higherfrequency of neural tube detbcts than singletons. All acadiac twins die and about one thirds of the pumped twin die in perinatal period. structures. 4. ACARDIA AMORPHUS - which has no discernible cephalic ortruncal structures. According to Krause W and Bejdl W (1948) Compression of the cephalic pole of the embryo prohibiting curving and fusion of the primitive heart tube has been suggested to @ the basic cause of this anomaly. As the umbilical cord of the acardiac twin is usually hypotrophic, it is likely to be torn during manipulation resulting in death of normal fetus due to blood loss through anastomosis. (Sanfilippo J er al lg79) According to Monie IW ( Ig70) most acardiacs are reported to have single umbilical aftery indicating penistence' of transitory single artery phase (which is normal upto carnegie stage 12). Allen VMI et al (1983) found thar about half of the cases studied by him had " Since the goal in such case is intemrption of vascular anastomosis between pump and recipient twin, improved imagrng techniques like two dimensional, tlree dimensional, and transvaginal ultrasonographic Doppler have made diagnosis of acardia possible even in chromosomal abnormalities even though the condition is said to be sporadic. An abnormal karyotype was found in perfused twin, while karyotype was foundnormal in pump twin. the first trimester of pregnancy by DETECTING INVERSION OF According to study by Groeninghen VJC et al (1985) acardiacs had normal karyotype. VASCULAR FLOW in recipient acardiac twin. (Dhall U et al 2005). CONCLUSION Early diagnosis may allow measures to be taken that may help to reduce the risk if such The present case of Acardia acephalus is one of the two patterns of hemodynamically complications by prenatal planning for si gnifi cant anastomotic circul ations, unique to monozygotic, monochorionic twin pregnancy. (Cunningham FG et al 2005). Acardia acephalus gains importance in view of complex placental, vascular anastomotic pattern in multiple gestation. A reported fifty percent mortality in pump twin is noted usually neonatal surgery. REFERENCES 1. Allen VMI, Smith DW Shepard TH, 1983. Twin reversed arterial perfusion (TRAP) sequence. A study of L4twin pregnancies with acardius. Seminars in Perinatology. 7 :285 -292. 80 1985. An acardiac acephalic monster. 2. Craven C., Ward K, Spellaey WN. Iggg.Embryo, fetus and placenta: Normal andAbnormal. Danforth's ' Case report and review. European journal of Obsteffics & Gynecology Reproductive Biolog-y. 1 9 : 3 ll -325 . 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Two monsters in a triplet pregnacy. New York State Journal of Medicine. 245-247 .