Song Kun Kong Beihua (Qilu Hospital, Shandong University, Jinan, Shandong, 250012, China) Ovarian tumors in pregnancy are not uncommon clinically. In the past, they were usually diagnosed during obstetrical checkups, cesarean deliveries, or when the tumor reversed or ruptured and became an acute abdominal condition. In recent years, with the common use of ultrasound in prenatal examination, more patients are diagnosed during pregnancy, therefore, the incidence is reported to be higher than before, accounting for about 1%-2% of all pregnant women. Ovarian malignancy combined with pregnancy is not uncommon and is the second most common malignant tumor of the female reproductive system during pregnancy, generally accounting for 2% to 3% of all ovarian tumors during pregnancy. The majority of adnexal masses during pregnancy are asymptomatic functional (physiological) cysts, such as corpus luteum cysts and follicular cysts, which mostly resolve spontaneously in mid-pregnancy. Among the benign tumors of pregnancy, mature teratomas (dermatomatous cysts) are the most common, accounting for about 50%, followed by plasmacytic and mucinous cystadenomas. Malignant tumors are mainly epithelial ovarian cancer and germ cell tumors. The incidence of germ cell tumors is the same or slightly lower than that of epithelial carcinoma, with asexual cell tumors being the most common; junctional tumors account for a significant proportion of epithelial carcinomas, and invasive carcinomas are mostly early and highly differentiated, so the overall prognosis of patients with ovarian cancer combined with pregnancy is better. Ultrasonography is an important diagnostic tool for ovarian tumors in pregnancy, and can determine the nature of tumors and guide further treatment; MRI can be used if ultrasonography is not clear, and its diagnostic value is even better than ultrasonography, but it is more expensive; tumor markers such as CA125 and AFP are of little diagnostic value, because their serum values are the same as estrogen, progesterone and β-hCG during pregnancy. CEA is not elevated during pregnancy and has some diagnostic value. Song Kun, Department of Gynecology, Qilu Hospital, Shandong University, the treatment of ovarian tumors in pregnancy is complicated and requires comprehensive consideration of various factors such as clinical manifestations, tumor pathological types and maternal fetal prognosis. Especially for patients with malignant tumors, the treatment of the mother’s disease will inevitably affect the intrauterine development of the fetus, leading to miscarriage, preterm delivery and even fetal congenital defects, which involves ethical and moral issues. Therefore, a comprehensive evaluation of the disease is needed when choosing a treatment plan, while fully respecting the informed choice of the mother and her family members. The incidence of ovarian tumors in pregnancy is relatively low, and most of the relevant studies are retrospective case studies with small samples. There is no evidence-based medical evidence to clarify the treatment guidelines, so clinical work needs to realize “individualized treatment” according to the actual situation of different patients. When ovarian tumors are detected during pregnancy, the first step is to determine the histological type of the tumor based on its size, morphology and Doppler flow characteristics, and to decide the treatment modality. Lerner et al. invented an ultrasound scoring system to predict the risk of malignancy of tumors, and the risk of malignancy was low for cystic, single-atrial, and <5 cm in diameter; moderate for cystic, multi-atrial, complex structure, and fine intra-tumor septum; and high for solid, multi-nodular, thick intra-tumor septum, and >5 cm in diameter. High risk. This scoring system has a negative predictive value of 99.6% and can successfully diagnose benign tumors. However, the diagnosis of tumor depends on pathological examination, and this scoring system is only for clinical reference and cannot be used as a universal standard yet. Patients with asymptomatic ovarian tumors in pregnancy with a low risk of malignancy can be treated conservatively (expectant therapy), and more than 90% of adnexal masses may spontaneously resolve or decrease in size after mid-pregnancy (around 16 weeks of gestation) as pregnancy progresses. If the tumor persists, most authors believe that elective surgery should be performed in mid-pregnancy to avoid torsion, rupture or obstruction of the birth canal as the uterus grows with pregnancy; some authors choose to follow up asymptomatic patients only and perform elective surgery or cesarean section after delivery to remove the tumor at the same time, and to perform emergency surgery if the tumor complicates an emergency abdomen. Both of these management options can lead to good pregnancy outcomes. Surgical treatment is suitable for: (1) ultrasound indicates complex tumor structure, high suspicion of malignancy and/or tumor diameter >6 cm, or rapid tumor growth; (2) tumor complications such as torsion, rupture, infection, bleeding or obstruction of the birth canal affecting delivery; (3) tumor persists during pregnancy. It is worth noting that even if the ultrasound shows complex ovarian tumor structure or large diameter, the risk of malignancy is still not high. If the patient also has ascites or large omental thickening, malignancy should be highly suspected and requires active surgical investigation. In cases of pregnancy combined with tumor with acute abdominal manifestations such as torsion and rupture, the mother’s life can be endangered. For large simple cysts, some authors have reported that fine needle aspiration of cystic fluid has achieved good results and can prevent complications such as cyst torsion and rupture, saving the pregnant patient from surgical treatment and obtaining good maternal and child outcomes. Surgical approach and timing of surgery In recent years, laparoscopic surgery has become the standard procedure for benign ovarian tumors. For patients in pregnancy, laparoscopic surgery is feasible if the risk of tumor malignancy is low in the preoperative evaluation and the operator has extensive experience in laparoscopic operation. Tumor complications causing acute abdomen are not a contraindication to laparoscopic surgery. The advantages of laparoscopic surgery are minimally invasive, fast postoperative recovery, short operative time and hospital stay, and low incidence of postoperative complications such as poor incision healing, pelvic and abdominal adhesions, and thrombotic disease, so laparoscopic treatment of benign tumors combined with pregnancy has gradually increased in recent years. However, the physiological characteristics of pregnancy make laparoscopic surgery technically more difficult: the enlarged uterus needs to be avoided during trocar placement to prevent uterine perforation and uterine wall damage, carbon dioxide pneumoperitoneum can cause hypercapnia and uterine hypoperfusion and affect the fetus, and the enlarged uterus affects the surgical field. Therefore, laparoscopic surgery should be performed in collaboration with experienced anesthesiologists and surgeons, and postoperative management should be improved. Whether laparoscopic surgery increases the rate of fetal loss is currently controversial, and the authors who support laparoscopic surgery are laparoscopic surgeons, so there is some bias. The therapeutic advantages of laparoscopic surgery for benign ovarian tumors in pregnancy have not been established because of the low incidence and the inability to collect enough cases for a randomized controlled clinical study. A longitudinal incision in the lower abdomen should be chosen for open surgery to allow adequate exposure of the adnexal region and to facilitate the expansion of the operation if intraoperative pathology confirms a malignant tumor. Whether open or laparoscopic surgery, intraoperative stimulation of the uterus should be avoided as much as possible to prevent miscarriage and preterm delivery. Mid-term pregnancy is the best time to operate for patients with ovarian tumor combined with pregnancy. It is generally considered safer to operate at 16 to 18 weeks of gestation because the placenta replaces the corpus luteum and the uterus is less sensitive, which reduces the rate of fetal loss; the fetus has completed the development of major organs, which can avoid fetal malformation caused by perioperative drugs; the physiological cysts can regress on their own at this time, while those that persist are mostly superfluous tumors; the uterus is of suitable size, which is conducive to surgical operation. Some authors have compared pregnancy outcomes in patients operated before or after 23 weeks of gestation, with a significantly higher rate of fetal loss in the latter. Laparoscopic surgery is usually performed in early or mid-trimester pregnancies; an enlarged uterus in late pregnancy makes it difficult to perform laparoscopic surgery. Therefore, except in cases of suspected malignancy, elective surgery in late pregnancy can be performed after the fetus has matured and delivered, or the tumor can be removed at the same time as the cesarean section. Surgery is indicated for complications such as tumor torsion and rupture at any stage of pregnancy. In early pregnancy, after destruction of the corpus luteum or adnexal resection, postoperative progesterone supplementation is required to avoid luteal insufficiency and induced miscarriage. For full-term pregnancies, cesarean section can be chosen to terminate the pregnancy and remove the ovarian tumor at the same time. However, for those who have already removed the tumor or have a small tumor, it is expected that torsion, rupture, or obstruction of the birth canal during delivery is less likely, they should be given the opportunity to deliver via vaginal delivery. The principles of treatment for patients with combined malignant ovarian tumors in pregnancy are the same as those for non-pregnant patients. If ovarian tumor in pregnancy is suspected to be malignant, it should be actively explored by open abdomen. If the tumor is clearly ovarian cancer, its further management should take into account the patient’s gestational age, tumor pathological type, tumor stage and subjective wishes of the mother and family. The treatment of malignant ovarian tumor in pregnancy involves ethical and moral issues and requires consideration of both the mother and the fetus. In general, the overall principle is to treat the mother’s disease and not to delay treatment in order to maintain pregnancy, resulting in poor prognosis for the mother. Fortunately, a significant proportion of tumors in pregnant patients are germ cell tumors, and the use of prenatal ultrasound has enabled most patients to be diagnosed at an early stage with a good prognosis for the disease. In the available literature, unless the tumor significantly encroaches on the uterus, the uterus is usually preserved until fetal maturity and a good pregnancy outcome is achieved, with a prognosis for the mother similar to that of the nonpregnant patient. As with non-pregnant ovarian malignancies, surgery and chemotherapy are the mainstay of treatment for ovarian cancer in pregnancy. Full staging surgery is the cornerstone of ovarian cancer treatment, and all patients should undergo surgical staging to determine subsequent treatment options. All patients should undergo surgical staging to determine the subsequent treatment plan. Germ cell tumors are sensitive to chemotherapy, so early stage patients should undergo conservative surgery, with resection of the affected adnexa, preservation of the contralateral ovary (bilateral ovarian tumors need to be excluded) and the pregnant uterus, as well as staging surgery: cytological examination of abdominal irrigation fluid, pelvic peritoneal biopsy, greater omentum resection, sampling of pelvic and para-aortic lymph nodes, and postoperative chemotherapy according to the staging decision. The prognosis is the same as non-pregnant. The prognosis is good. Most patients can be treated by tumor resection or adnexal resection, and even if the tumor recurs, reoperation can achieve good results. Patients with invasive epithelial ovarian cancer have the worst prognosis. Early stage patients undergo full staging surgery and late stage patients undergo tumor cytoreductive surgery, all of which require adjuvant chemotherapy after surgery. If the mother expects to maintain the pregnancy, the fetus can be maintained until maturity after surgery + chemotherapy for patients in the middle and late stages of pregnancy; for patients in the early stages of pregnancy, termination of pregnancy should be recommended because the chances of miscarriage, fetal malformation and other adverse pregnancy outcomes due to surgery and chemotherapy are significantly higher at this time. The need for chemotherapy in patients with ovarian cancer in pregnancy depends on tumor stage, histologic type and tumor cell differentiation. All malignant germ cell tumors and invasive epithelial ovarian cancer require postoperative adjuvant chemotherapy except for early stage, highly differentiated tumors (stage IA or IB, G1, G2). The standard chemotherapy for germ cell tumors is the PEB/PVB regimen; the standard chemotherapy for epithelial ovarian cancer is the PT regimen, but most authors use single-agent platinum-based chemotherapy in pregnancy to reduce toxicity, although there are case reports of paclitaxel chemotherapy not causing adverse fetal outcomes. In addition to maternal side effects, chemotherapy in pregnant patients needs to pay special attention to the toxicity of chemotherapeutic agents on the embryo and fetus, especially teratogenicity, and the timing of chemotherapy should be used as a reference. In early pregnancy, chemotherapy should be avoided because the fetal malformation rate of single dose chemotherapy reaches 10%, and the malformation rate of combined chemotherapy is even higher, and chemotherapy can also lead to early abortion; in middle and late pregnancy, fetal organs except brain and gonads are fully developed, and chemotherapy is relatively safe. Most of the current literature reports that chemotherapy in mid- and late-term pregnancies can achieve good pregnancy outcomes, with no malformations in the newborn and normal physical and mental development in the short term. There is no reliable information on long-term complications such as offspring malignancies, congenital defects, and long-term physical and mental development. It is important to note the existence of “selective bias” and the preference of many authors to publish cases with good outcomes. There are only a few reports of neonatal defects such as spina bifida, hearing loss, and complications such as fetal growth restriction and myelosuppression due to chemotherapy during pregnancy. The fact that all chemotherapy drugs are FDA graded C, D and X makes informed choice by the mother and family crucial. In addition, the timing of pregnancy termination should be chosen after 2 weeks of chemotherapy, because the myelosuppression caused by chemotherapy is most severe at this time and can cause serious delivery complications; also, the placenta can help the fetus metabolize chemotherapy drugs, and the placental circulation of the newborn is aborted after birth, and delivery within a short period of time after chemotherapy will cause toxic drugs to accumulate in the newborn. In conclusion, most of the ovarian tumors combined with pregnancy are physiological cysts, which can spontaneously regress with the progress of pregnancy and can be treated conservatively. The persistence of tumors with large diameter and complex ultrasound structure suggest malignant tumors should be treated with active surgery. For benign tumors, laparoscopic surgery is safe and effective; for malignant tumors, different treatment options are used according to the stage of the disease, tissue type, gestational age and the subjective wishes of the mother, so as to achieve “individualized treatment”. The best time for surgery is mid-term pregnancy, especially 16 to 18 weeks of pregnancy; surgery should be performed decisively for suspected malignant tumors without considering the time limit of pregnancy; surgery for emergency abdominal conditions arising from tumor complications. Most malignant tumors can be treated with conservative surgery + postoperative adjuvant chemotherapy to achieve good maternal and child outcomes.