探讨单绒毛膜双胎(MCT)早产儿罹患坏死性小肠结肠炎(NEC)的临床特点。

选择2021年2月11日与1月18日，于青岛大学附属医院采取剖宫产术分娩的2例MCT罹患NEC女性早产儿(No.1、2患儿，均系MCT之小)为研究对象。采用回顾性研究方法，收集No.1、2患儿的临床病例资料，并对其临床表现、诊治进行分析。以"twins""twins pregnancy""multiple pregnancy""monochorionic twins""neonatal necrotizing enterocolitis""双胎""双胎妊娠""单绒毛膜双胎""新生儿坏死性小肠结肠炎"为关键词，在PubMed、中国知网、万方数据知识服务平台中，检索MCT罹患NEC患儿诊治相关研究文献；文献检索时间设定为上述数据库建库至2021年8月。本研究经过本院伦理委员会批准(审批文号：QYFY WZLL 26856)。

①临床病例资料分析：No.1、2患儿均无双胎输血综合征(TTTS)及双胎反向动脉灌注序列征(TRAPS)等并发症。No.1患儿出生胎龄为34⁺⁵周，出生体重为1 790 g，生后10 min因"早产、呻吟吐沫"被收治入院。生后第9天便血、第11天腹胀，腹部X射线摄片见肠壁积气，腹部超声见门静脉积气，被诊断为NEC。生后第11天开腹探查术见部分回肠坏死，接受坏死肠管切除术和小肠造瘘术。术后第10天，患儿对母乳喂养耐受差，体重不增；第48天改为深度水解配方奶喂养，仍不耐受；第60天时，接受小肠造口还纳术和小肠吻合术，术后回肠组织病理学活检显示，肠黏膜组织呈慢性炎症。本次术后母乳喂养及增加奶量均顺利，住院86 d好转出院；随访至2021年12月时，其矫正月龄为9个月，体格、语言、运动发育正常。No.2患儿出生胎龄为35⁺⁶周，出生体重为2 390 g，生后14 min因"早产、生存能力低下"被收治入院。生后第4天便血，腹部X射线摄片见腹部肠管扩张、积气，被诊断为NEC。给予胃肠减压、禁食和抗菌药物等治疗后逐渐好转。生后第26天出现腹胀，腹部造影见结肠狭窄；于生后第33天接受结肠切除术与吻合术，术后结肠组织病理学活检显示肠黏膜组织呈慢性炎症，术后恢复较好，住院49 d好转出院；随访至2021年12月时，其矫正月龄为10个月，体格、语言、运动发育正常。②文献复习结果：根据本研究设定的文献检索策略，共计检索到3篇关于MCT罹患NEC诊治的国外文献，纳入MCT罹患NEC患儿为6例，产前均并发TTTS，3例采取胎儿镜下胎盘交通血管激光凝固术治疗TTTS，3例未采取任何TTTS产前干预措施。这6例MCT罹患NEC患儿，再加上本研究的2例，共计8例患儿的平均出生胎龄为28周，平均出生体重为1 176 g，男、女性患儿各为4例，发生NEC的平均时间为生后9 d。对8例该病患儿均采取手术治疗，最终5例存活，3例死亡。

对于未发生TTTS、TRAPS等双胎相关并发症的MCT早产儿，也可能由于存在胎盘血流动力学不稳定等，导致小肠缺血缺氧等而增加发生NEC风险。对MCT早产儿肠道功能谨慎评估，可使其NEC得到早诊断、早治疗，进而改善其预后，降低新生儿死亡率。

To investigate clinical characteristics of neonatal necrotizing enterocolitis (NEC) in preterm infants with monochorionic twins (MCT).

Two cases of MCT preterm baby girl with NEC who were delivered by cesarean section in the Affiliated Hospital of Qingdao University on February 11 and January 18, 2021 (case 1 and case 2, both of them were the second of MCT) were selected into this study. Clinical data of case 1 and 2 were collected by retrospective study method, and their clinical manifestations, diagnosis and treatment were analyzed. Literature about NEC in MCT was retrieved with key words of " twins" " twins pregnancy" " multiple pregnancy" " monochorionic twins" " neonatal necrotizing enterocolitis" both in Chinese and English, based on PubMed, China National Knowledge Infrastructure, and Wanfang Data Service Platform. Literature retrieval time was set from the establishment of above databases to August 2021. This study was approved by the Ethics Committee of the Affiliated Hospital of Qingdao University (Approval No. QYFY WZLL 26856).

①Clinical data analysis: case 1 and 2 had no complications of twin-twin transfusion syndrome (TTTS) and twins reversed arterial perfusion sequence (TRAPS). Case 1 was born at 34^{+ 5} gestational weeks with birth weight of 1 790 g. She was hospitalized in department of neonatology 10 min after birth due to " premature birth, groaning and spit" . She was diagnosed as NEC because of hematochezia on the 9th day after birth, and had abdominal distension on the 11th day after birth, intestinal wall gas observed by abdominal X-ray examination, and portal vein gas observed by abdominal ultrasound. On the 11th day after birth, by exploratory laparotomy showed part of intestinal necrosis, necrotic bowel resection and enterostomy were performed. Case 1 had poor tolerance of breast-fed on day 10 postoperatively, and without weight gain. On day 48 postoperatively, she was fed with deeply hydrolyzed formula milk, but still feeding intolerance. Loop stoma reversal and intestinal anastomosis were performed on day 60 after previous operation. Her postoperative pathological biopsy of ileum showed that the intestinal mucosa was chronically inflamed. Case 1 received breastfeeding after the second operation, and the milk was added smoothly. Case 1 was discharged after 86 days of hospitalization. Follow-up to December 2021, her corrected age was 9-month, and her physical, language, and motor development were normal. Case 2 was born at 35^{+ 6} gestational weeks with birth weight of 2 390 g. Case 2 was hospitalized in department of neonatology due to " premature birth and low viability" 14 minutes after birth. She had hematochezia on day 4 after birth. She was diagnosed as NEC because of abdominal intestinal dilatation and gas accumulation were observed by abdominal X-ray examination. After treatment with gastrointestinal decompression, fasting and antibacterial drugs, her symptoms gradually improved, but abdominal distension occurred on day 26 after birth, and by abdominal angiography showed intestinal stenosis. Colectomy and anastomosis were performed on day 33 after birth. Her postoperative pathological biopsy of colon tissue showed chronic inflammation of intestinal mucosa, and she was discharged on day 49 of hospitalization. Follow-up to December 2021, her corrected age was 10-month, and her physical, language, and motor development were normal. ②Literature review results: according to retrieval strategis formulated in this study, 3 pieces of abroad literature related to NEC in MCT were retrieved, among which 6 cases of NEC in MCT were included. These 6 cases of NEC in MCT all were complicated with TTTS before birth, and 3 cases were treated with fetoscopic laser photocoagulation of communicating vessels for TTTS, while the other 3 cases did not receive any prenatal interventions for TTTS. Analysis results of the total of 8 cases of MCT preterm infants with NEC included 2 cases in this study were as follows. The average gestational age of them was 28 weeks, average birth weight was 1 176 g, 4 case were newborn baby boys and 4 cases were nweborn baby girls, and average onset time of NEC was 9 days after birth. All 8 cases of preterm infants were treated by surgery for NEC, and 5 cases survived, 3 cases died.

Even for MCT preterm infants without complications related to twins such as TTTS and TRAPS, the risk of NEC in MCT preterm infants might be increased due to placental hemodynamics instability and intestinal ischemia and hypoxia. Careful assessment of the intestinal function of MCT preterm infants can enable early diagnosis and early treatment of NEC, thereby improving its prognosis and reducing neonatal mortality.