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OEIS complex


Thursday 9 February 2006

Definition: The OEIS malformative complex associates an omphalocele, an exstrophy of the cloaca (cloacal exstrophy), an anal imperforation (imperforate anus or anal atresia) and spinal defects.

This rare complex is thought to represent the most severe end of a spectrum of birth defects, the exstrophy-epispadias sequence, which, in order of increasing severity, includes phallic separation with epispadias, pubic diastasis, vesical exstrophy of the bladder and cloacal exstrophy, and OEIS complex.

The incidence of the OEIS complex is very rare, estimated to occur in 1 of 200,000-400,000 pregnancies. Majority of cases are sporadic Very few instances of recurrence of anomalies in this cluster have been reported.

In the OEIS (omphalocele-exstrophy-imperforate anus-spinal defects) complex, exstrophy of the cloaca includes the persistence and exstrophy of a common cloaca that receives ureters, ileum, and a rudimentary hindgut and is associated with failure of fusion of the genital tubercles and pubic rami, incomplete development of the lumbosacral vertebrae with spinal dysraphism, imperforate anus, cryptorchidism and epispadias in males and anomalies of the mullerian duct derivatives in females, and a wide range of urinary tract anomalies. Omphalocele is common, and most patients have a single umbilical artery.


- omphalocele
- vesical exstrophy or cloacal exstrophy

  • A common cloaca receives ureters, ileum, and a rudimentary hindgut and is associated with failure of fusion of the genital tubercles and pubic rami.

- imperforate anus (anal atresia)
- spinal defects

  • - spina bifida

- failure of fusion of the genital tubercles and pubic rami
- incomplete development of the lumbosacral vertebrae with spinal dysraphism,
- cryptorchidism and epispadias in males
- anomalies of the mullerian duct derivatives in females
- wide range of urinary tract anomalies
- single umbilical artery
- 11 pairs of ribs
- omphalocele
- imperforate anus (anal atresia)
- duplicated colon
- intestinal malrotation
- anteriorly placed anus
- rectovaginal fistula

-  genital malformations in females

  • Ambiguous genitalia
  • Hypoplastic labia
  • Bifid uterus

- genital malformations in males

  • Small penis
  • Ambiguous genitalia
  • Epispadias
    - abnormal scrotum or absent scrotum
  • widely separated labioscrotal folds
  • cryptorchidism

- hydronephrosis
- renal agenesis
- pelvic kidney
- duplicated collecting system
- hydroureter
- cloacal exstrophy
- vesicovaginal fistula
- hemivertebrae
- absent sacrum
- sacral segmentation defects
- symphysis pubis diastasis
- congenital hip dislocation
- club feet
- tethered cord
- lipomyelocystoceles
- meningomyelocele
- Chiari malformation (Arnold-Chiari syndrome)
- hydrocephalus


The etiology of the OEIS complex is still unclear, single defects in blastogenesis and mutations in homeobox genes, such as HLXB9, have been suggested to be responsible for the development of the OEIS complex. Moreover, higher incidence of OEIS in monozygotic twins suggests a possible genetic contribution to the occurrence of this multisystem defect.

- del(3)(q12.2q13.2) (15887303)
- monogenic anomaly

  • OEIS in dizygotic twin pregnancy (16113551)

See also

- glomerulocystic kidney diseases (GKDs)


- Hong R, Lim SC, Jang JW, Suh CH, Jeon HJ, Lee MJ, Kim YS. OEIS complex with glomerulocystic kidney disease: a case report. Pediatr Dev Pathol. 2007 Mar-Apr;10(2):121-4. PMID: 17378687

- Vasudevan PC, Cohen MC, Whitby EH, Anumba DO, Quarrell OW. The OEIS complex: two case reports that illustrate the spectrum of abnormalities and a review of the literature. Prenat Diagn. 2006 Jan 31; PMID: 16450352

- Kosaki R, Fukuhara Y, Kosuga M, Okuyama T, Kawashima N, Honna T, Ueoka K, Kosaki K. OEIS complex with del(3)(q12.2q13.2). Am J Med Genet A. 2005 Jun 1;135(2):224-6. PMID: 15887303

- Bohring, A. : OEIS complex, VATER, and the ongoing difficulties in terminology and delineation. (Letter) Am. J. Med. Genet. 107: 72-76, 2002. PubMed ID : 11807874

- Carey, J. C. : Exstrophy of the cloaca and the OEIS complex: one and the same. (Letter) Am. J. Med. Genet. 99: 270 only, 2001. PubMed ID : 11251991

- Martinez-Frias, M. L.; Bermejo, E.; Rodriguez-Pinilla, E.; 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. 99: 261-269, 2001. PubMed ID : 11251990

- Keppler-Noreuil KM. OEIS complex (omphalocele-exstrophy-imperforate anus-spinal defects): a review of 14 cases. Am J Med Genet. 2001 Apr 1;99(4):271-9. PMID: 11251992

- Kallen K, Castilla EE, Robert E, Mastroiacovo P, Kallen B. OEIS complex—a population study. Am J Med Genet. 2000 May 1;92(1):62-8. PMID: 10797425

- Lee, D. H.; Cottrell, J. R.; Sanders, R. C.; Meyers, C. M.; Wulfsberg, E. A.; Sun, C.-C. J. : OEIS complex (omphalocele-exstrophy-imperforate anus-spinal defects) in monozygotic twins. Am. J. Med. Genet. 84: 29-33, 1999. PubMed ID : 10213043

- Smith, N. M.; Chambers, H. M.; Furness, M. E.; Haan, E. A. : The OEIS complex (omphalocele-exstrophy-imperforate anus-spinal defects): recurrence in sibs. J. Med. Genet. 29: 730-732, 1992. PubMed ID : 1433234

- Schinzel, A. A. G. L.; Smith, D. W.; Miller, J. R. : Monozygotic twinning and structural defects. J. Pediat. 95: 921-930, 1979. PubMed ID : 501497

- Carey, J. C.; Greenbaum, B.; Hall, B. D. : The OEIS complex (omphalocele, exstrophy, imperforate anus, spinal defects). Birth Defects Orig. Art. Ser. XIV(6B): 253-263, 1978.