Fetus in fetu

Rare: estimated incidence of 1/5.000.000 live births.

Presence of a structure resembling a dead fetus (known as parasitic or non-dominant twin) in or outside the body of a living child. This fetal structure is well encapsulated (in what is actually the remnants of its amniotic sac), composed of all embryonic tissues and many fetal organs (except the brain and the heart) and connected to the alive child  by a peduncle containing thrombosed vessels .

The most frequent locations are the retroperitoneum (72 %), the oropharynx, the abdominal organs.


The pathogenesis is unknown: disorder of the division of the multipotent cells of the inner layer of the blastocyst ?; form of well-differentiated teratoma (but a teratoma does not contain any vertebral structures and has a strong potential for malignant degeneration) ?; very early death of a siamese twin ?

As 'fetus in fetu' and teratoma are quite similar, it is wise to follow the α1-fetoprotein postoperatively.



Anesthetic implications: 

depending on the location and the volume of the parasitic structure .


References : 

-         Spencer R.
Parasitic conjoined twins: external, internal (fetuses in fetu and teratomas), and detached (acardiacs).
Clin Anat 2001; 14: 428-44.

-        Reddy RK, Kannaiyan L, Srirampur S, Malleboyina R, Irfan GM, Sharab H, Kannepalli S.
Thoracic fetus in fetu.
J Indian Assoc Pediatr Surg. 2012;17 :178-9.

-        Hoeffel CC, Nguyen KQ, Phan HT, Truong NH, Nguyen TS, Tran TT, et al.
Fetus in fetu: a case report and literature review.
Pediatrics 2000;105:1335- 44

-        Escobar MA, Rossman JE, Caty MG.
Fetus-in-fetu: report of a case and a review of the literature.
J Pediatr Surg 2008;43: 943-6.

-        Bajaj AK, Dave N, Garasia MB. 
A rare case of oral fetus in fetu with mandibular cleft and absent hyoid. 
Pediatr Anesth 2011 ; 21 : 706-7.

-         Cingel V, Durdik S, Babala J, Polak S, Varga I. 
Fetus in fetu from newborn’s mediastinum: case report and a review of litterature
Surg Radiol Anat 2011 

-        Prescher LM, Butler WJ, Vachon TA, Henry MC, Latendresse T, Ignacio RC Jr.
Fetus in fetu: review of the literature over the past 15 years.
J Pediatr Surg Case Reports 2015 ; 3 : 554e562

-        Akodjenou J., Bori Bata A-K., Gbenou A.S.,  Guedenon M., Houngbadji M., Sansuamou E., Maroufou J.A., Zoumenou E., Bazin J.E., Veyckemans F. 
Anesthetic management of an intrathoracic Fetus in Fetu case in a 5 months old infant at a low resources African Sub-Saharian hospital.
American Journal of Pediatrics 2021; 7: 198-202.


Updated: October 2022