Breast cancer is the most common malignancy diagnosed in the female population worldwide and the leading cause of death among perimenopausal women. Screening is essential, since earlier detection in combination with improvements in breast cancer treatment can reduce the associated mortality. The aim of this study was to review and compare the recommendations from published guidelines on breast cancer screening. A total of 14 guidelines on breast cancer screening issued between 2014 and 2022 were identified. A descriptive review of relevant guidelines by the World Health Organization (WHO), the U.S. Preventive Services Task Force (USPSTF), the American Cancer Society (ACS), the National Comprehensive Cancer Network (NCCN), the American College of Obstetricians and Gynecologists (ACOG), the American Society of Breast Surgeons (ASBrS), the American College of Radiology (ACR), the Task Force on Preventive Health Care (CTFPHC), the European Commission Initiative on Breast Cancer (ECIBC), the European Society for Medical Oncology (ESMO), the Royal Australian College of General Practitioners (RACGP) and the Japanese Journal of Clinical Oncology (JJCO) for women both at average and high-risk was carried out. There is a consensus among all the reviewed guidelines that mammography is the gold standard screening modality for average-risk women. For this risk group, most of the guidelines suggest annual or biennial mammographic screening at 40–74 years, while screening should particularly focus at 50–69 years. Most of the guidelines suggest that the age limit to stop screening should be determined based on the women’s health status and life expectancy. For women at high-risk, most guidelines recommend the use of annual mammography or magnetic resonance imaging, while the starting age should be earlier than the average-risk group, depending on the risk factor. There is discrepancy among the recommendations regarding the age at onset of screening in the various high-risk categories. The development of consistent international practice protocols for the most appropriate breast cancer screening programs seems of major importance to reduce mortality rates and safely guide everyday clinical practice.

Importance: Monochorionic (MC) twin pregnancies are at risk of unique fetal and obstetric complications, which require increased surveillance and specific interventions to minimize the associated neonatal morbidity and mortality. Objective: This review aimed to evaluate and compare the most recently published influential guidelines on the management of monochorionic twin pregnancies. Evidence Acquisition: A comparative review of guidelines from the Royal College of Obstetricians and Gynaecologists (RCOG), the Society of Obstetricians and Gynaecologists of Canada (SOGC), the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG), the International Federation of Gynecology and Obstetrics (FIGO), and the International Society of Ultrasound in Obstetrics and Gynaecology (ISUOG) was carried out. Results: All the reviewed guidelines recommend the determination of chorionicity and amnionicity in the first trimester, along with the precise labeling of the twins and confirmation of the gestational age based on the crown-rump length of the larger twin or the dates of assisted reproductive techniques. They also encourage the performance of aneuploidy screening during the first trimester, using either a combined nuchal translucency and biochemical markers test or cfDNA. A detailed anatomy scan is recommended, with emphasis on the fetal cardiac assessment. There is agreement on the recommended ultrasonographic surveillance protocol, the diagnostic criteria of TTTS, TAPS, and TRAP, the optimal timing of delivery in case of uncomplicated MC twins, and the need for earlier delivery in case of complications or MCMA twins. All the reviewed medical societies provide similar recommendations regarding the management of pregnancies complicated by TTTS, TAPS, discordant fetal anomaly, and demise of one co-twin. Minor discrepancies were identified regarding the diagnosis and management of sFGR, the routine assessment of cervical length, as well as the first-line aneuploidy screening method. Conclusions: Multiple pregnancies pose significant maternal, fetal, and obstetric risks compared with singleton pregnancies, with MC twins being at the highest risk of adverse perinatal outcomes, particularly in the absence of increased surveillance or therapeutic interventions. The development and implementation of consistent international evidence-based practice guidelines for the prompt diagnosis and management of MC twin pregnancies and their associated complications may contribute to more favorable outcomes.