先天性巨結腸(Hirschsprung’s discase，HD)是先天性結腸疾病。主要由於直腸或結腸遠端的肌間神經叢細胞缺乏，導致腸道持續痙攣，使得大便在近端結腸淤滯，造成該腸段肥厚性擴張。最先由Hirschspmn在1888年對此疾病做出詳細的描述，之後在1901年Tittle首次提出本病與神經節細胞缺乏有關，在1964年Ehrenpries詳細論述本疾病的病因和致病機轉。(a congenital disorder of the colon in which certain nerve cells, known as ganglion cells in the myenteric plexus, are absent, resulting in a persistent over-stimulation of nerves within the affected region, causing contraction and chronic constipation。This disease is named after Harald Hirschsprung, the Danish physician who first described the disease in 1888)。

長久以來認為Hirschsprung’s discase是一種多因素所造成的疾病，包括遺傳與營養。1993年最新研究指出，本病具有明顯的家族遺傳傾向，與染色體第10對異常有很大關係(For a long time, Hirschsprung’s was considered a multi-factorial disorder, where a combination of nature and nurture were considered to be the cause. However, in 1993, two articles by independent groups in Nature Genetics said that Hirschsprung’s disease could be mapped to a stretch of chromosome 10)。目前認為本病是受累腸段遠端肌間神經叢細胞缺如所致，所以又稱congenital aganglionic megacolon。

在新生兒中發病率為1/2000～1/5000，位居新生兒消化道畸形第 2位，男：女= 4.3：1。9% Hirschsprung’s discase可以伴發Downs Syndrome( 9% of the Hirschsprung cases were also diagnosed as having Downs Syndrome)。長久以來認為Hirschsprung’s discase是一種多因素所造成的疾病，包括遺傳與營養。2003年最新研究指出，本病是基因編碼兩種蛋白質異常有關，第10對染色體的RET 原癌基因與第13對染色體EDNRB基因異常是被確定的。胚胎發育時期，RET編碼的蛋白質主要與消化道的運動有關；EDNRB編碼的蛋白質主負責消化道內神經細胞間的連接。更新的研究指出，EDNRB 基因序列的異常對本病的發生發展至關重要。(RET codes for proteins that assist cells of the neural crest in their movement through the digestive tract during the development of the embryo. …EDNRB codes for proteins that connect these nerve cells to the digestive tract). This means that the absence of certain nerve fibers in the colon could be directly related to these two genes mutating so the wrong proteins are produced. new research suggests that mutations in genomic sequences involved in regulating EDNRB have a bigger impact on Hirschsprung’s disease than previously thought)

另外RET基因突變又與唐氏症(Downs syndrome)、甲狀腺癌(thyroid cancer) 及神經母細胞瘤( neuroblastoma)發生有關。所以，Hirschsprung’s  disease患者併發Downs syndrome、thyroid cancer and neuroblastoma比一般正常人群來的多(RET can mutate in many ways and is associated with Downs syndrome、thyroid cancer and neuroblastoma，which have also been observed in Hirschsprung’s patients with greater frequency than in the general population)。

1. 頑固性便秘(Constipation)與腹脹(Abdominal distension)
   患兒因腸管痙攣長度不同而有不同的臨床表現。痙攣段越長，出現便秘越早也越嚴重。痙攣段不長者，經直腸指檢或溫鹽水灌腸後可排出大量胎糞(meconium)及氣體，日後也須經常灌腸才能排便(Delayed passage of meconium)。
2. 營養不良與發育遲緩
   因長期腹脹與便秘，食慾下降，營養吸收不足。結腸肥厚性擴張，使腹部出現寬大的腸型，可觸摸到充滿大便的腸管及糞石。
3. 伴發小腸結腸炎
   是最常見和最嚴重的併發症，可引起滲出性腹膜炎，表現為突然高燒、血壓下降、嚴重腹脹、嘔吐、腹瀉，造成脫水與酸中毒，治療延誤可引起死亡。主要是近端結腸繼發肥厚性擴張，加上一些患兒免疫功能異常，使得腸壁血液循環不良所引起。也有人認為是細菌和病毒感染所致，但大便培養多無致病菌生長。

正常新生兒有90%在出生後24小時內排出胎糞，99%新生兒最遲在48小時內排出。凡新生兒出生後48小時後無胎糞排出，並伴有腹脹和嘔吐者，均應懷疑是Hirschsprungs disease (Hirschsprungs disease is suspected in a baby who has not passed meconium within 48 hours of delivery. Normally, 90% of babies pass their first meconium within 24 hours, and 99% within 48 hours)。其他包括理學檢查，結合影像學的觀察基本即可確診。

Definitive diagnosis is made by suction biopsy of the distally narrowed segment

1. 腹部觸診：可摸到擴張的結腸腸型。
   
2. 直腸指診：首先指感直腸壺腹有空虛感，無大量胎糞滯積，並且手指拔出後，隨即就有大量的胎糞及許多臭氣排出(explosive stools after a doctor inserts a finger into the rectum, lots of gas and bloody diarrhea)，這種“爆發式”排泄後，同時腹脹即有好轉，對診斷很有幫助。
   
3. X-ray：可見結腸充氣擴張，在腹周邊呈連續空柱狀透亮區，小腸脹氣，但直腸壺腹無氣體，無大的液平面等表現，可與小腸梗阻相互鑒別。
   
4. 鋇劑灌腸X-ray：準確率90％以上。(A barium enema is the mainstay of diagnosis of Hirschsprung’s, though a rectal biopsy showing the lack of ganglion cells is the only certain method of diagnosis)。可見病變的直腸狹窄，呈漏斗狀，與擴張的腸段相接，結腸蠕動強烈而規則。排鋇後由於腸壁和黏膜增厚，可見腸腔內有明顯皺褶，稱為“結腸空腸化”改變。
   
5. 直腸組織切片檢查(rectal biopsy)：操作難度大，容易誤診，並非所有患者都須做此項檢查。
6. 直腸內壓測定(anorectal manometry)：由於患兒對直腸擴張後無法引起肛門括約肌鬆弛，也缺乏肛門直腸反射，所以當氣囊充氣時，肛管內壓力無法下降，就可懷疑是先天性巨結腸。

1. 慢性便秘
   
2. 急性小腸結腸炎
   
3. 腸穿孔
   
4. 水電解質代謝紊亂
   
5. 繼發感染性休克

痙攣腸段短、便秘症狀輕者，可先採用綜合性非手術療法，包括定時用等滲鹽水洗腸（灌洗出入量要求相等，忌用高滲、低滲鹽水或肥皂水），擴肛、緩瀉藥，以避免糞便在結腸內淤積。若上述方法無效，雖為短段巨結腸也應手術治療。若痙攣腸段長，便秘嚴重者，必須進行根治性手術，目前採用最多的手術為：

1. 拖出型直腸乙狀結腸切除術(Swenson’s手術)：The Swenson procedure leaves a small portion of the diseased bowel.
   
2. 結腸切除-直腸後結腸拖出術(Duhamel’s手術)：The Duhamel procedure uses a surgical stapler to connect the good and bad bowel.
   
3. 直腸粘膜剝離-結腸於直腸肌鞘拖出切除術(Soave’s手術)：The Soave procedure leaves the outer wall of the colon unaltered. The Boley procedure is just a small modification of the Soave procedure. The term "Soave-Boley" procedure is sometimes used.