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 Table of Contents  
Year : 2017  |  Volume : 6  |  Issue : 4  |  Page : 291-296

OEIS complex - a rare developmental anomaly

1 Associate Professor, Department of Anatomy, Pushpagiri Institute of Medical Sciences and Research Centre, Thiruvalla, Kerala, India
2 Professor, Department of Neonatology, Pushpagiri Institute of Medical Sciences and Research Centre, Thiruvalla, Kerala, India
3 Junior resident, Department of Anatomy, Pushpagiri Institute of Medical Sciences and Research Centre, Thiruvalla, Kerala, India

Date of Submission08-Jul-2017
Date of Acceptance24-Jul-2017
Date of Web Publication24-Nov-2019

Correspondence Address:
Gaddam Vijaya Lakshmi
Associate Professor, Department of Anatomy, Pushpagiri Institute of Medical Sciences and Research Centre, Thiruvalla, Kerala - 689 101
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Source of Support: None, Conflict of Interest: None

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OEIS complex is a rare congenital anomaly comprising of the following four components: Omphalocoele, Exstrophy of cloaca, Imperforate anus and Spinal defects. It forms the extreme end of exstrophy-epispadias complex [EEC] of congenital defects. It is associated with anomalies of gastro-intestinal, urinary and genital systems. External genitalia are bifid, if present. Etiology is not clear. It can be diagnosed by prenatal ultrasound on visualization of’diaper type’ of distribution of anomalies, along with malformations of the limbs. The condition causes severe psychosocial trauma to the parents and family members. In live births, surgical interventions in several stages, are performed by skilled expertise only at selected tertiary health care centers. Outcome is highly variable. Prenatal identification of the condition is necessary to give adequate counselling, and have proper planning of the delivery and postnatal management of the baby.

Keywords: omphalocoele, cloacal exstrophy, spinal anomalies, mesodermal migration

How to cite this article:
Lakshmi GV, Abraham J, Mathew DS. OEIS complex - a rare developmental anomaly. Natl J Clin Anat 2017;6:291-6

How to cite this URL:
Lakshmi GV, Abraham J, Mathew DS. OEIS complex - a rare developmental anomaly. Natl J Clin Anat [serial online] 2017 [cited 2022 Dec 7];6:291-6. Available from: http://www.njca.info/text.asp?2017/6/4/291/298228

  Introduction Top

OEIS is an acronym coined by Carey et al in 1978 to describe a congenital condition having Omphalocoele, exstrophy of cloaca, Imperforate anus and Spinal defects[1]. It is the most severe form of a group of midline abdominal malformations called Exstrophy-Epispadias Complex [EEC][2]. The association of cloacal exstrophy with omphalocoele, imperforate anus and spinal defects was first described by Littre in 1709, much before the acronym OEIS came into use[3].

Apart from the four major components of the condition, genital, renal and limb anomalies are frequently encountered. There is failure of fusion of the genital tubercles resulting in bifid phallus or clitoris. Alternatively, there are reports of absent external genitalia. Gonads and other internal genital organs are frequently absent. When present, there could be associated cryptorchidism in males and mullerian duct anomalies in the females. Pubic diastasis, agenesis of parts of pelvic bones, spinal dysraphism and other spinal defects are also associated with this condition[4],[5].

  Case Presentation Top

A 28 year old primi came at 29 weeks 4 days gestation with severe pre-eclampsia. She was a known case of post-renal transplant and gestational hypertension on nifidipine, clonidine, azathioprine and prednisolone. She had been on regular antenatal checkups. Family history was positive for hypertension.

Anomaly scan at 15-16 weeks detected multiple congenital anomalies in one twin; the other twin being normal. Findings on the ultrasonogram at 29 weeks showed the following anomalies in one twin: a large omphalocele with visceral contents, cystic mass in abdominopelvic region [? Sacrococcygeal teratoma], kyphoscoliosis in mid- thoracic region, myelomeningocoele, ascites and bilateral mildhydronephrosis. The othertwinhad no anomalies.

An emergency lower segment caesarian section was performed. The first baby was a female, pre-term and healthy with normal external morphology. The second baby was live with multiple anomalies, who did not cry immediately, and succumbed within three hours. The baby was donated to the department of Anatomy for academic purpose.

External examination showed a huge omphalocoele [ruptured during delivery] with exposed contents. [Figure 1]. Anterior abdominal wall was absent. Below the omphalocoele, a large cloacal aperture was noted. The umbilical cord was attached to the upper part of the aperture and bifurcated around the margins of the aperture. External genitalia were absent and anus was imperforate. Through the cloacal aperture, the hemibladder plates were identified on either side of the everted hindgut. [Figure 2].
Figure 1: Omphalocoele

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Figure 2: Cloacal Exstrophy
Yellow arrows : umbilical cord bifurcating around margins of cloaca Green arrows : Hemibladder; Red arrow: Everted hindgut

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Mid-thoracic kyphoscoliosis, lumbo-sacral myelomeningocoele and foot deformities were evident [Figure 3]. Placenta was single and gave attachment to two umbilical cords [Monochorionic, diamniotic]. The cord of the affected twin was short and adherent to placenta [Figure 1].
Figure 3: Spinal & skeletal anomalies

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Autopsy revealed the intestines, the normal liver, gall bladder, spleen and stomach inside the omphalocoele sac. Non-return of midgut loop was noted with absent duodenal rotation and fixation. Duodenum led into a dilated, proximal midgut segment, which narrowed down into a distal midgut segment [Figure 4], The distal mid-gut segment opened onto the top of the posterior wall of cloaca [Figure 5].
Figure 4: Display of omphalocoele contents.
The forceps points to the junction between proximal and distal parts of the midgut

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Figure 5: Structures opening onto cloaca
Green arrow – Distal midgut; Blue arrow – Everted hindgut Probe 1 – Opening of midgut onto of everted hindgut Probe 2 – Leads into lumen of hindgut rudiment

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The lower part of cloaca led into the hindgut rudiment [Figure 5]. The hind gut rudiment had an external appearance of a cyst, with thick walls, on the lower part of the posterior abdominal wall [Figure 6]. It measured 3.5 cm x 1.2 cm. Its anterior wall was everted in the lower part and formed the posterior wall of cloaca below the opening of the midgut [Figure 5], It was supplied by the inferior mesenteric artery. On opening it, the contents were solid and greenish in colour, suggestive of meconium. Histopathology revealed features of large intestinal mucosa [Figure 7].
Figure 6: Cyst on posterior abdominal wall [green arrow] Hindgut rudiment

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Figure 7: Histopathology of cyst wall shows mucosa of large intestine along with smooth muscle.

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The two kidneys, adrenals and ureters were identified, on either side of the hindgut rudiment. The ureters were enlarged and traced up to the posterior wall of cloaca [Figure 8], Pancreas and diaphragm appeared normal. Gonads and other internal genital organs were absent.
Figure 8: Ureters opening into cloaca
Blue arrow – excised hintgut rudiment; Yellow arrows–Right kidney and ureter; Green arrows – Left kindney and ureter

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Further dissection revealed pubic diastasis [Figure 9], kyphoscoliosis in mid-thoracic region, agenesis of lower part sacrum, myelomeningocoele and posterior dislocation of the femora [Figure 10].
Figure 9: Pubic diastasis [red arrow]

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Figure 10: Dissection of back
Asterisk femoral head [bilateral posterior dislocation]; Red arrow – sacral rudiment; Yellow arrow - Lower end of spinal cord after opening meningomyelocoele

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Post-mortem radiogram revealed marked thoracic scoliosis, hemi vertebrae and butterfly vertebrae, partial agenesis of sacrum, 10 ribs on left side and 11 ribs on right side [Figure 11].
Figure 11: Postmortem radiogram - PA view
Yellow Arrow – partial agenesis of sacrum; Red arrow - kyphoscoliosis.

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  Discussion Top

OEIS affects 1 in 2,00,000 - 4,00,000 live births. Considering the still births and terminated pregnancies, it was estimated to have a frequency of 1 in 27,174 pregnancies. Sex preponderance is inconclusive due to varied reports by different authors[2].

Cloacal exstrophy was earlier described under several names like ectopia cloacae, vesico-intestinal fissure and exstrophia splanchnia[1]. It is considered to be the most severe form of the EEC, which comprises of a spectrum of anterior abdominal defects, from epispadias, through bladder exstrophy to cloacal exstrophy[2].

Cloacal exstrophy was described to be one of the four components of the OEIS complex by Carey et al in 1978[1]. The authors, later on, have opined that the cloacal exstrophy is almost always accompanied by the other three components of the OEIS complex. Since then, cloacal exstrophy and OEIS complex were used to mean the same[6].

The exstrophied cloaca classically comprises of the bladder hemi plates on either side of a hindgut plate, which is commonly referred to as the caecal plate. The terminal part of the midgut opens into the top of everted shortened hindgut rudiment. The hemi bladders receive the openings of the ureters[2].

Apart from the four major anomalies given by the acronym, other deformities affecting the limbs, pelvis, renal and genital system have also been described[3],[4],[5]. The present case also had associated limb anomalies, pubic diastasis, posterior dislocation of femora, absent external and internal genitalia.

Prenatal diagnosis can be done as early as the 13th week[3]. Prenatal ultrasound helps in identification of the “diaper-type of distribution” of the defects namely, omphalocoele, non-visualization of the urinary bladder and lumbosacral neural tube defects. Other associated anomalies like limb defects, renal and genital malformations can also be identified[7]. Associated elevated alpha fetoprotein levels have been reported in several studies[3],[5],[7]. Early prenatal diagnosis helps in providing the appropriate advice.

Several embryonic mechanisms have been described in the development of OEIS complex. It is caused by a primary polytopic field defect occurring in early blastogenesis or due to defective mesodermal migration in early embryonic period[8]. Mechanical obstruction to mesodermal migration into the region of ventral body wall, with simultaneous failure in convergence of the embryonic folds, results in the non-development of lower anterior abdominal wall, and thereby causing bladder or cloacal exstrophy[9].

In the absence midline ventral body wall, the umbilical cord is inserted caudally into the cloacal membrane, leading to its instability and premature rupture[10]. Premature rupture of cloacal membrane has been shown to cause cloacal exstrophy. The timing of the premature rupture [4-6 weeks] was crucial in determining the severity of malformations[11].

Defect in ventral abdominal wall, reduces the scope of return of the physiological hernia and gut-fixation[4]. The mesodermal migration into the caudal regions is essential for the formation of the urorectal septum and the vertebrae. Failure of mesodermal migration leads to persistence of the common cloacal chamber, defective vertebral development and spinal dysraphism. Proctadaeum fails to develop in cloacal exstrophy, manifesting as imperforate anus[8].

Etiology of OEIS complex is not well established. OEIS had been reported in monozygotic twins[12], dizygotic twins[13] and in siblings of separate pregnancies in the same family[3]. The condition is more frequent in monozygotic twins compared to dizygotic twins[12]. Mutations in homeobox gene, HLXB9, are associated with this condition[14]. Though chromosomal anomalies like 47 XXX, trisomy 18 and 21 have been reported in association with this disorder[15], normal karyotyping has also been noted in cases with this disorder[3],[7]. Microarray and sequencing of the candidate genes could not establish causative relation with any single mutation[16].

Maternal diabetes, peri-conceptional maternal exposure to smoking and drugs like diazepam and hydantoin have also been reported to be associated with its development[14]. In the present case, the patient was taking nifedipine, clonidine, low dose prednisolone [US FDA category C] and azathioprine [US FDA category D]. Guidelines issued by FDA warrant the use of these drugs in pregnant women when potential benefits outweigh the risk to the foetus[17],[18].

Recent literature states that all the above four drugs are considered safe in post-renal transplant pregnant women[19]. An isolated dominant mutation could have been the etiology in the present case since both the twins shared the same environment in utero, and the other twin is normal. Moreover, OEIS complex has been reported more often in absence of exposure to maternal diabetes, smoking and known teratogens, pointing to a dominant mutation or subclinical maternal disorder[3].

Management of surviving cases is mainly surgical, and involves multidisciplinary approach. The primary aim is to achieve closure of the bladder and anterior abdominal wall, diverting colostomy, followed by urethroplasty, bladder neck reconstruction and ureteral re-implantations, anal canal reconstruction, genital reconstruction and closure of spinal defects. Functional restoration of the anal canal, bladder and psychosexual development poses a great challenge, with variable outcomes[20],[21].

  Conclusion Top

OEIS complex is a rare congenital anomaly with poor prognosis. Amidst a background of debatable etiology, the present case rules out the role of environmental factors in causing the condition, since the other twin [monochorionic gestation], who shared the same environmental conditions in utero, is normal. A single dominant mutation during early phase of cleavage is more likely to be the causative agent.

Conflicts of interest : None

Financial Support : None

  References Top

Carey JC, Greenbaum B, Hall BD. The OEIS complex [omphalocele, exstrophy, imperforate anus, spinal defects]. Birth Defects 1978;14:253-63. https://www.ncbi.nlm.nih.gov/pubmed/728566  Back to cited text no. 1
Ebert A, Reutter H, Ludwig M AND Rosch W H The Exstrophy-epispadias complex Orphanet Journal of Rare Diseases 2009, 4:23 doi:10.1186/1750- 1172-4-23  Back to cited text no. 2
Smith NM, Chambers HM, Furness ME, Haan EA: The OEIS complex [omphalocele-exstrophy- imperforate anus-spinal defects]: recurrence in sibs. J Med Genet 1992,29:730-32 http://dx.doi. org/10.1136 /jmg.29.10.730  Back to cited text no. 3
Subhadra Devi V, Md K Faheem N, Vidyavathi Ch, Usha Rani V. OEIS COMPLEX - A RARE CASE REPORT. International Journal of Research & Development of Health. Jan 2013; Vol l[l]:21-25 http://www.ijrdh.com/files/6%20oeis%20article.pdf  Back to cited text no. 4
Mallikajjunappa B, Ghosh A. OEIS COMPLEX: A rare Case Report with Review of Literature. JIMSA January-March 2014;27[l]:24-25  Back to cited text no. 5
Carey, J. C. Exstrophy of the cloaca and the OEIS complex: one and the same. [Letter] Am. J. Med. Genet 2001; 99: 270. http://medind.nic.in/jav/ tl4/il /javtl 4il p24.pdf  Back to cited text no. 6
Ben-Neriah Z, Withers S, Thomas M, Toi A, Chong K, Pai A, Velscher L, Vero S, Keating S, Taylor G and Chitayat D. OEIS complex: prenatal ultrasound and autopsy findings. Ultrasound Obstet Gynecol 2007; 29:170-177 DOI: 10.1002/uog.3874  Back to cited text no. 7
Martmez-Frias, M.L., Bermejo, E., Rodriguez-Pinilla, E. and Frias, J.L. , Exstrophy of the cloaca and exstrophy of the bladder: Two different expressions of a primary developmental field defect. Am. J. Med. Genet, 2001 ;99:261-269. doi: 10.1002/ajmg. 1210  Back to cited text no. 8
Muecke EC: The role of the cloacal membrane in exstrophy: the first successful experimental study. J Urol 1964, 92:659-667. https://www.ncbi.nlm.nih. gov/pubmed/14241195  Back to cited text no. 9
Vermeij-Keers C, Hartwig NG, Werff JF Van der: Embryonic development of the ventral body wall and its congenital malformations. Semin Pediatr Surg 1996,5:82-89.  Back to cited text no. 10
Thomalla JV, Rudolph RA, Rink RC, Mitchell ME: Induction of cloacal exstrophy in the chick embryo using the C02 laser. J Urol 1985, 134:991-995. https://doi.org/10.1016/S0022-5347fl7j47573-2  Back to cited text no. 11
Lee DH, Cottrell JR, Sanders RC, Meyers CM, Wulfsberg EA, Sun CC. OEIS complex [omphalocele- exstrophy-imperforate anus-spinal defects] in monozygotic twins. Am J Med Genet 1999; 84:29-33. https://www.ncbi.nlm.nih.gOv/pubmed/l 0213043  Back to cited text no. 12
Noack F, Sayk F, Gembruch U. Omphalocele exstrophy imperforate anus-spinal defects complex in dizygotic twins. Fetal Diagn Ther. 2005;20:346-348. DOI 10.1002/ajmg.a.31897  Back to cited text no. 13
Shanske AL, Pande S, Aref K, Vega-Rich C, Brion L, Reznik S, Timor-Tritsch IE. Omphalocele-exstrophy- imperforate anus spinal defects [OEIS] in triplet pregnancy after IVF and CVS. Birth Defects Res A Clin Mol Teratol 2003; 67:467-471. DOI: 10.1002/bdra. 10058  Back to cited text no. 14
Kallen K Castilla EE, Robert E, Mastroiacovo P, Kallen B. OEIS complex- a population study. Am JMed Genet. 2000;92:62-68. doi: 10.1002/[SICI] 1096- 8628[20000501]92:1<62::AID-AJMG11>3,O.CO;2-B  Back to cited text no. 15
Vlangos CN, Siuniak A, Ackley T, van Bokhoven H, Veltman J, et al. Comprehensive genetic analysis of OEIS complex reveals no evidence for a recurrent microdeletion or duplication. Am J Med Genet A 2011;155:38-49. DOI: 10.1002/ajmg. a.33757  Back to cited text no. 16
https:// chemm.nlm.nih.gov/pregnancycategories.htm accessed on 09/08/2017at 12:15pm  Back to cited text no. 17
https:// www.drugs.com accessed on 09/08/2017 at 12:15pm  Back to cited text no. 18
Silvi Shah and Prasoon Verma, “Overview of Pregnancy in Renal Transplant Patients,” International Journal of Nephrology, vol. 2016, Article ID 4539342, 7 pages, 2016. http://dx.doi.org /10.1155/2016/45393 42  Back to cited text no. 19
Patel A, Gupta AS. OEIS Complex. JPGO 2015. Volume 2 No. 3. http://www.jpgo.org/2015/03/oeis- complex.html  Back to cited text no. 20
Manassero-Morales G, Franco-Bustamante K, Matos-Rojas I . OEIS Complex, A Case Report. J Intensive & Crit Care 2016,2:1. DOI: 10.21767/2471 -8505.100013  Back to cited text no. 21


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11]


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