Evidence map›Paper›PMID 42839228›Full record

ArticleBasic and clinical andrology2026

Automated Bergmann-Kliesch Score assessment in testicular biopsies using artificial intelligence-based whole-slide image analysis: a retrospective monocentric development and validation study.

Simon Gassen, Nadine Flinner, Ingvild Frøberg Mathisen, Julia Bein, Ole Beldermann, Lukas Haug, Jens Köllermann, Felix Chun, Annette Bachmann, Kerstin Lehr and 2 more

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Article in Basic and clinical andrology, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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1 · What the graph read from it

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2 · The registry

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3 · Its place in the literature

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4 · The record

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5 · Who and what money

Authors and funding

12 authors.

Simon GassenDr. Senckenberg Institutes of Pathology, Neuropathology and Human Genetics, Goethe University Frankfurt, Frankfurt am Main, Germany.ORCID http://orcid.org/0009-0003-8423-4153
Nadine FlinnerDr. Senckenberg Institutes of Pathology, Neuropathology and Human Genetics, Goethe University Frankfurt, Frankfurt am Main, Germany.
Ingvild Frøberg MathisenDr. Senckenberg Institutes of Pathology, Neuropathology and Human Genetics, Goethe University Frankfurt, Frankfurt am Main, Germany.
Julia BeinDr. Senckenberg Institutes of Pathology, Neuropathology and Human Genetics, Goethe University Frankfurt, Frankfurt am Main, Germany.
Ole BeldermannDr. Senckenberg Institutes of Pathology, Neuropathology and Human Genetics, Goethe University Frankfurt, Frankfurt am Main, Germany.
Lukas HaugDr. Senckenberg Institutes of Pathology, Neuropathology and Human Genetics, Goethe University Frankfurt, Frankfurt am Main, Germany.
Jens KöllermannDr. Senckenberg Institutes of Pathology, Neuropathology and Human Genetics, Goethe University Frankfurt, Frankfurt am Main, Germany.
Felix ChunDepartment of Urology, University Medical Center Frankfurt, Goethe University Frankfurt, Frankfurt am Main, Germany.
Annette BachmannDepartment of Obstetrics and Gynecology, University Medical Center Frankfurt, Goethe University Frankfurt, Frankfurt am Main, Germany.
Kerstin LehrDepartment of Obstetrics and Gynecology, University Medical Center Frankfurt, Goethe University Frankfurt, Frankfurt am Main, Germany.
Robin S Mayer *Dr. Senckenberg Institutes of Pathology, Neuropathology and Human Genetics, Goethe University Frankfurt, Frankfurt am Main, Germany.
Peter J Wild *Dr. Senckenberg Institutes of Pathology, Neuropathology and Human Genetics, Goethe University Frankfurt, Frankfurt am Main, Germany. peter.wild@unimedizin-ffm.de.ORCID http://orcid.org/0000-0002-1017-3744

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundThe Bergmann-Kliesch Score is a histopathological grading system used to evaluate spermatogenesis in testicular biopsies, quantifying the fraction of seminiferous tubules containing elongated spermatids. It serves as a key parameter in the clinical process of men with non-obstructive azoospermia (NOA) undergoing testicular sperm extraction (TESE) for subsequent intracytoplasmic sperm injection (ICSI). Manual Bergmann-Kliesch Score assessment is time-consuming and subject to inter- and intraobserver variability. This study aimed to develop and validate an artificial intelligence (AI)-based computational pipeline for automated Bergmann-Kliesch Score assessment from digitized testicular biopsy whole-slide images (WSIs).

resultsA retrospective monocentric cohort of 74 patients who underwent TESE at the University Medical Center Frankfurt was analyzed. A dual-model machine-learning pipeline was used to process paired haematoxylin-eosin (HE) and OCT3/4 immunohistochemically stained WSIs. A U-Net architecture with a ResNet-34 backbone was trained on 60 HE-stained slides for tubular segmentation, monitored by a multi-class Dice coefficient of 0.897 on the validation set. A second U-Net model with a ResNet-34 backbone was trained on 15 OCT3/4-stained slides comprising 14,226 manually annotated elongated spermatids for spermatid detection. Both modalities were integrated via multimodal image registration combining rigid alignment and B-spline warping, enabling spatial projection of spermatid detections onto tubular segmentations. On the patient-level held-out test set of 15 patients, AI-derived Bergmann-Kliesch Scores showed strong agreement with pathologist-assigned reference scores (Pearson r = 0.957, Spearman ρ = 0.856, R

conclusionsThis AI-based pipeline enables automated, reproducible Bergmann-Kliesch Score assessment from routinely stained testicular biopsy WSIs, demonstrating strong agreement with manual pathologist evaluation. The system shows promise as a clinical decision-support tool in TESE workflows. External multicentric validation and prospective correlation with ICSI outcome data are warranted in future studies.

Indexed as

Bergmann-Kliesch ScoreDeep learningDigital pathologyICSIImage registrationNon-obstructive azoospermiaSpermatogenesisTESETesticular biopsyWhole-slide image analysis

Identifiers

PMID42839228
PMCPMC13640392

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.