Cervical insufficiency is also known as endocervical atresia and cervical laxity. In patients with cervical insufficiency, the cervix contains less fibrous tissue, elastic fibers and smooth muscle, or it is pathologically dilated and relaxed due to fracture of the fibrous tissue at the endocervix and reduced ability of the sphincter at the isthmus. Cervical insufficiency The main manifestations of cervical insufficiency are preterm labor and mid- and late-term recurrent miscarriages, with an incidence of 8% to 15% for recurrent miscarriages. Causes of cervical insufficiency 1. congenital cervical insufficiency: about 1/3 of patients with cervical insufficiency are due to congenital factors, often accompanied by abnormal development of Mullerian ducts, such as unicornuate uterus or longitudinal uterus, or may be cervical histological defects and insufficient cervical elastin content. 2. Acquired cervical insufficiency: There are several types: (1) Birth injury. Injury to the cervical opening caused by childbirth and cervical dilation during surgery, such as emergency delivery, huge children, breech traction, forceps, etc. (2) The cervical dilatation during abortion is too fast and too violent. In recent years, the incidence of traumatic cervical insufficiency has been increasing due to the increase of early abortion and induction of labor in mid-pregnancy. There are even some charlatans who give infertility patients what dilation for conception, which not only does not have any therapeutic effect, but also causes infection and cervical insufficiency to occur. (3) It can also occur secondary to anatomical changes in the cervix or lower segment of the uterus, such as the occurrence of myomas. (3) Physiological cervical insufficiency: It has been suggested that the endocervical sphincter acts as a functional sphincter during pregnancy and that patients with subclinical uterine contraction or hypotonic endocervical sphincter have a diminished endocervical sphincter. In addition, pineapple protease and papain may relax the cervix. Cervical insufficiency, which cannot withstand the increase in intrauterine pressure with increasing gestational months, often results in abortion with spontaneous rupture of the amniotic membrane in the middle of pregnancy, which can expel completely normal embryonic tissue. Diagnosis: (1) History: The typical history is of spontaneous rupture of the fetal membranes in late mid-trimester, followed quickly by delivery of a completely normal fetus, and each pregnancy is delivered earlier than the previous one. (2) Cervical examination: Palpation of the cervix during non-pregnancy, with a short and relatively flaccid isthmus that can be passed through the internal cervical opening without resistance with a #8 Hegar dilator, is a simple way to diagnose cervical insufficiency. (3) Foley catheter traction test: The Foley catheter is placed into the uterine cavity and lml of water is injected into the catheter sac to make its diameter reach 6mm, so that it can be easily pulled out of the endocervix (traction force is less than 600mg) that is, cervical insufficiency is suspected and the diagnosis should be further confirmed. (4) Hysterosalpingography: The average diameter of the isthmus is 2.63 mm under normal conditions, but the average diameter of the isthmus increases significantly in cervical insufficiency, and the angle of the lower uterine segment of the cervical canal disappears. (5) Ultrasonography: Transabdominal, perineal or vaginal ultrasound is the most common and effective method to diagnose cervical insufficiency during pregnancy. An endocervical diameter of ≤19 mm in midtrimester can exclude cervical insufficiency, while a diameter of ≥23 mm can confirm the diagnosis. A beak-like or funnel-shaped entry of the fetal membranes into the endocervix is also one of the ultrasound images used to diagnose cervical insufficiency, and this sign is often seen before the shortening of the cervix. Cervical length >30mm is normal; length <20mm indicates significant shortening of the cervix and suggests miscarriage or preterm delivery. Treatment】Including general treatment and surgical treatment. (1) General treatment: ① bed rest; ② progesterone; use 17-hydroxyprogesterone 500-1000mg/week; ③ contraction inhibitor, such as β-adrenergic receptor stimulant Zodopa, firstly intravenous injection, after contraction suppression, change to oral 40mg once every 8h. Pay attention to the heart rate of the pregnant woman during the course of the medication, it is prohibited for those who have heart disease; ④Silicone condom: place this condom as far as possible at the top of the vagina around the cervix, after placement the condom gradually expands. It is removed in late pregnancy or when labor is initiated. (2) Surgical treatment: Non-pregnant surgical methods, including the scratch method, Palmer-Lash method, and Mann method. Their main purpose is to strengthen the isthmus by removing the weakness of the cervix and isthmus or by localizing fibrosis, but they can be followed by scar formation in the cervical canal and infertility or difficulty in expelling intrauterine material, so they are rarely used. Surgery during pregnancy: Surgery is often performed at 14 to 18 weeks of pregnancy, but in recent years surgery at 20 weeks of pregnancy has also achieved better results. It can also be monitored with ultrasound after pregnancy and operated if the inner cervical opening is ≥ 23 mm in diameter or if the membranes are bird's beak and funnel shaped and the length of the cervix is 20 mm. Commonly used methods are: ①Shirodkar loop ligation; ②McDon-aid loop ligation. The former requires upward pushing of the bladder, while the latter does not. It is clinically proven to be simple, rapid, and has a good prognosis. Postoperative application of contraction inhibitors such as β-adrenoceptor stimulants (Zoldoba) or retention of epidural anesthesia catheter for local administration until one week postoperative extubation, strict infection control, and prohibition of sexual intercourse. Secondary infection is often the main cause of surgical failure. In addition, the Wurm method of suturing is used in cases of loss of the cervical canal, dilatation of the uterine orifice and fetal membrane bulge. Complications of surgery include bleeding, infection, rupture of membranes, preterm labor, bladder injury, obstructed labor, cervical necrosis, uterine rupture, and infertility. Surgery is contraindicated in the following cases: unexplained uterine bleeding; amnionitis; ruptured membranes; 4 cm dilatation of the uterine opening; formal labor; severe fetal abnormalities; and fetal death.